While we may not all agree with the fact that the decisions was done without a suspect test, there have been instances of Quick Bans within other metas. The reason people will be upset about this Quick Ban is that most Suspect Tests are led with discussion like the discussion that occurred before this, but rather than a suspect test, there was just a ban following it. There is nothing we can do in regards to the ban, and while there are people upset here, there are people that are looking this that are overjoyed as well.
With the rise of Talonflame came the rise of flying monos in general. Flying monos rely on a core of Skarmory, Landorus (I usually more than T), Thundurus, Talonflame, a Zard, Togekiss/Something more support oriented. Talonflame inarguably made flying monos more offensive, but we can expect to see Flying Mono usage decrease a little, despite its still overpowered nature. Flying will likely look towards Staraptor to fill Talonflame's role, but I'm expecting to see the odd usage of Swellow or some other glass cannon Pokemon in the place of it. Talonflame was used as a fast attacker, but typically abused its priority over anything else. Flying will recover just fine from this change due to the access to a lot of Pokemon that sport its power (like Staraptor) that also have access to Scarf or other methods to outspeed.
As far as item usage, fighting/grass/bug teams will probably see a bigger change in their items than their team composition. Rocky Helmet Ferrothorn was mentioned earlier in the thread as a means to rack damage up on Talonflame. This was not an uncommon set before. The item that will likely see a decreased usage is sash, for the Pokemon that had no means of surviving otherwise. I've seen sashes on Pokemon such as Keldeo as well based on where I am on the monotype ladder, so I know that people don't just sash Pokemon like Breloom to survive hits like this. I think, given the nature of these teams, there will also be a definite shift in Mega Usage. For bug, either Mega Scizor, Mega Pinsir, or Mega Heracross all really didn't care for seeing Talonflame, but the biggest benefit here is Mega Pinsir. At base 105, Pinsir is just fast enough to outspeed some threats (Base 100 Pokemon without scarves in particular like the odd AV Victini, or Landorus at base 101). The lack of priority flying for Mega Pinsir will see a rise in usage of it, which may be the kiss of death for some people. Mega Pinsir recently fell from S Rank (in OU) due to the fact that, although it was capable of sweeping OU teams almost singlehandedly, it was horribly outclassed and threatened by Talonflame and the presence of Talonflame saw the usage of some more threatening walls to Pinsir. We are forced to acknowledge the fact that some threats such as Mega Pinsir will return due to this ban. For Fighting, both of these Megas saw usage despite the presence of Talonflame in the meta and will likely remain the same. Grass relied on Venusaur Mega and struggled to handle Talonflame as it was, so this may see a rise in popularity for, not only grass, but for poison (another type that struggled with fire teams).
Although Flying teams seem to be almost unaffected, most of the outcry I've personally seen has been from fire users. Talonflame sees two purposes on a fire team: 1.) High power 2.) Priority. High power isn't linked to its base attack, which doesn't even break 100, but to the fact that it had access to the recoil moves of its dual types that made it a threat. Acknowledging this high power, these following Pokemon all break base 110 Attack (favoring physical due to the fact that Talonflame was physical): Arcanine (110), Darmanitan (140), Entei (115), Charizard Mega X (130), Flareon (130), Emboar (123), and the incoming Volcanion (110. Of these Pokemon, Darmanitan, Charizard Mega X, and Flareon all receive abilities that further boost their attack, Sheer Force, Tough Claws, and Guts respectively. I do not expect to see usage of Flareon, but these three are all excellent candidates to fulfill the same task of power that Talonflame had. Victini should also be noted for its access to STAB V-Create at a base 180. Access to priority occurs in the following Pokemon, as well: Entei and Arcanine have access to Extremespeed, Infernape has access to Mach Punch and Vacuum Wave, and Emboar has access to Sucker Punch. Of these four, the only one that does not appear on the list of Pokemon with higher attacks is Infernape (With a respectable 102). It can also be noted that, with the exception of Charizard Mega-X, these are all Pokemon that are capable of running scarves for the speed side of priority. Entei is even very capable of running a band set.
As far as the composition of teams are concerned, I don't anticipate seeing Cradily used as much. Ferro counters flying well enough and Venusaur is capable of countering fire and there are few threats remaining that have access to both types of moves. Bug may see reduced use of Crustle and Armaldo (see the theme? Rock types, rock types everywhere), but ultimately, these Pokemon have other uses as well. It's more likely Armaldo will continue seeing use than Crustle though, as Armaldo has access to Rapid Spin. For fighting, Cobalion may not see any more use as that was the large reason it came into fighting monos earlier this gen. Otherwise, fighting should remain relatively stable. Flying and Fire may also choose to move away the hyper offense they have currently to find a new way to win to try and optimize their team, but due to the fact that Talonflame moved the meta into an offensive direction, even if Talonflame is now gone, people will try to replace it on their team rather than choose another route altogether. I don't agree with this method of fixing a team, as this will ultimately find you, as listed above, trying to replace it with a Pokemon like it. If Gale Wings were suspected and banned, Talonflame would lose usage, dramatically. Talonflame's use is its priority. These Pokemon listed above are not Talonflame, and ultimately, the people affected have options on what to do, but approaching a new team should be done while acknowledging the meta, not necessarily acknowledging what Talonflame was.