I agree, I meant more like that the Mega mechanic would be in the game, but some stones might be unavailable, as there would be two successive generation of them getting the sideline. If Gen 8 has a shiny new gimmick (which I hope it doesn't), then it's unlikely we will get any new megas since Gen 7 didn't have them either.
Z-Crystals seem even more gimmicky than Mega Stones, so it's probably easier for them to be sidelined, or even possibly removed from Gen 8 all together (but this is a stretch) as they haven't been as well received as Mega Pokemon. I'd argue that if either Mega Stones or Z-Crystals ended up getting the sideline, Z-Crystals would go first.
For Mega Stones I think it's going to be as worst as it gets: only Mega Stones for Pokemon in the regional dex will have their Mega Stones available (and maybe a few special cases). All others will be then given out for events or prizes for competition entry (or Global Missions/whatever may replace them in the future). Though even with this method that might mean for future generations there will be missing Mega Stones which will have an effect on the meta.
As for Z-Crystals, this would only be a problem for the Pokemon specific ones. I would be very easy to implement the elemental Z-Crystals some place. Though whether they'll shove it for post game like they did with Mega Stones is the main question. Now for Mega Stones it's actually okay for them to move it post game. I'd like to see them main game but honestly they'd get the most use post game. However since the elemental Z-Crystals can be used by all Pokemon I think it would be a shame to shove them post game a they can be used main game to give your Pokemon that extra kick it may need during a battle (course the game designers would have to plan for it and if they don't want to they may just shove it to post game for that reason). And then there's the issue of them introducing a Gen VIII gimmick (which I hope they kind of don't and instead focus expanding on Mega, Z-Crystals, and other mechanics they have. At most maybe have a way to combine Mega and Z-Crystals).
To be fair, codes for the Mega Stones have not been released yet. We don't know if the Mawilite and Beedrilite codes are going to be permanent. All we had is the tournament reward.
But then we have the Mewtwonites which are internet codes. They have no end date, but once they decide to end it there's no getting those Mega Stones again. Now, if GF keeps the event going until the release of Gen VIII, there's no problem because then the meta would move on and, as
R_N said, anyone playing the old games would be for the story and experience (at most to get a Pokemon to transfer) so not care what Pokemon or related item they can't get.
Pokemon Availability:
Speaking of which, I do agree GF needs to put some more focus on Pokemon variety and distribution. We have over 800 Pokemon now and they'll make more Pokemon each generation (maybe lesser than previous generations, which is good as that means they can focus on making those Pokemon good using previous gen Pokemon to fill in missing gaps). Each game should have about half the Pokedex available and each route should feel like they're introducing more Pokemon instead of keeping a same handful of Pokemon throughout all routes with some new additions. For Sun & Moon each island could have easily had 100 unqiue Pokemon, sharing only a few between islands. Also the new Pokemon should be on the forefront, this is THEIR generation. You make older generation favorites the rare finds, not the new ones.
However I don't want them to cram every single Pokemon in; no, that would be insane. I'm alright that you need to transfer up, makes it feel like having the previous games wasn't a waste. Sure you can use GTS, but that can be unreliable and you don't know exactly what you're getting. And to do whatever you want in the game the regional Pokemon suffice, you just got to work with the Pokemon your provided (and you can look up a guide if you're having problems).
I'd imagine a lot of the Pokemon that can't be obtained in Sun/Moon will be available in other games this generation, like how FR/LG/Colosseum/XD did with the Pokemon that weren't natively available in R/S.
Well to an extent. The next remakes would be Diamond & Pearl and I have two opinions on that: if we stick to the 3DS than I don't think we'll get it as ORAS was the 3DS remake (unless they feel the advancement between Gen VII and VI was significant enough, which to be fair was). Though if we do move the games to the Switch as being rumored then I'm sure we'll get them, though would it be before or after the 3rd version (if we get one, that is
*coughZcough*)?
However, even then we might not get all Pokemon available in one generation, though we don't need to unlike Gen III. Gen III needed to provide a way to get all existing Pokemon at that time due to one major factor: generation lockout. GB Advance games were incompatible with GB games, there was no way to transfer up, at least game between game. This also gave them a convenient excuse to completely restructure the IV and EV system to what they are today, further making them incompatible. The Colosseum games and remakes were the solution to there being no transferring up (the remakes then becoming a tradition, fans of the Colosseum games shouldn't hold their breath for another one any time soon).
tbh this is one of my biggest problems with gen 5. like i really like the region, and i like the pokemon, and i like playing them a lot. except - every single fucking time i start the game i have to get the c-gear and hear about the dream world and if im playing bw2 go through join avenue or whatever the fuck and it's honestly infuriating because it basically reads like the games were meant to be multiplayer (more than the rest of pokemon i mean) and I never once connected to the internet with gen 5, and nowadays i can't, but i also can't play the game without having to hear about how wonderful internet connectivity is.
like, the games that predate bw were hgss, and hgss didnt do that shit, and it gave you what is imo the best touch screen interface we ever had in pokemon, and then in gen 5 that all went out the window and it makes me so mad. You can have a game that focuses strongly on multiplayer. It's impossible to get all the pokemon in gen 1 without trading or glitches, that's been there since the beginning, so pokemon has always been a series that focuses strongly on multiplayer. But it's when you give a game a single player option, and then during that single player option never shut the fuck up about how amazing the (dead) multiplayer is, that I get annoyed. If I could pay for a copy of white and white 2 that just removed all that from the game I would in a heartbeat
This can just be swept under the umbrella of "unwanted forced tutorials". It's okay these tutorials exist, the problem is they're forced upon you and you can't skip through them. I have this same problem with ORAS's Super Contests and SM's Battle Royal, they force you into a tutorial for a side feature which I may have no interest in or would rather do later when I'm more prepared.
Latest annoying thing: Z-crystals don't "get" Hidden Power and Revelation Dance. Like, surely they could have figured out a way to make them "count" as the type of move they actually are instead of just using their technical Normal typing (allowing Oricorio to learn actual STAB moves from its non-flying types would also be acceptable).
Let me give my geisha bird ghost the ghost crystal, damn you.
It also annoys me that they clearly intended Arceus to be able to use Z-crystals instead of plates, and then totally gimped it by making Judgment not work with them.
For Hidden Power I sort of get why: though you just need a damaging move of a type to use the Z-Crystal of that type, that still means there are certain Z-Moves every Pokemon can't do. If Z-Crystals took Hidden Power's type into account, that means every Pokemon (that can learn Hidden Power) can use every elemental Z-Crystal. Seems a bit broken.
However for Revelation Dance and Judgement it should.
Sadly they kind of backed themselves up in a corner when they decided to let you change Oricorio's forms. Since you can change forms that means they all share a movepool and can't learn a move of move of their primary typing. Otherwise we'd get a Fire-type who has Water coverage, Psychic with Bug coverage... um, well Psychic and Ghost usually learn moves of each other... actually Oricorio is part Flying so why would it be worried about Bug coverage. You know what, I take it back. WHY doesn't learn the TMs of its primary type? Thinking about it there's no real reason (other than making Revelation Dance seem inconsequential but maybe you should just improve it instead of limiting Oricorio) it can't learn Flamethrower, Fire Blast, Thunderbolt, Thunder, Psychic, Psyshock, and Shadow Ball (and status moves like Will-O-Wisp and Thunder Wave).