To be honest, the two main fires leaving do open the door for Magmortar and Pyroar, to a lesser extent, to see increased usage and viability as they are no longer outclassed or seeing significant competition in fulfilling roles and specific niches on teams. While Magmortar will never be able to hit as hard as Specs Typhlosion, it is able to abuse high special attack in conjunction with strong fire STAB and coverage (which it has more of than Typh, to compensate for the inability to spam fire STAB due to less speed and strength than something like Specs Eruption Typhlosion). Thunderbolt, Focus Blast, HP Grass, Psychic, even Earthquake, and of course Fire Blast are all at the disposal of Magmortar which allows it to use AV or even LO, EBelt, etc. to take advantage of its coverage. Unlike Typhlosion, it's not the best option for a choice scarf or specs user (both are viable, but borderline mediocre, imo) as it is so much better when it can Thunderbolt a Mantine, HP Grass a Seismitoad, or Focus Blast a Regirock without having to make a risky prediction and lock-in to that move. Overall, it really has specially offensive capabilities that are arguably unparalleled in the tier and now it's untapped potential is being exposed at full force.
At this point you may be thinking, "damn, Magmortar must be even harder to deal with Typh. Should this get suspected now?" to which my answer would certainly be no.
Magmortar has 83 speed, compared to Typhlosion's 100 speed, which is lackluster in this metagame considering all offensive teams should at least have 2-3 quicker pokemon while all defensive teams should have 1-2 quicker pokemon (running full stall without a scarfer or at least a fast pokemon is never optimal in this day and age). It is prone to being "played around" which may be a generally weak argument as prediction is a two-way street and Magmortar doesn't lock into a move often as referenced above, but when there are so many things quicker and it has a hard time getting in healthily in the first place, Magmortar's window to offensively threaten fast teams is small. Likewise, it is still prone to being checked by the somewhat less common, but still noteworthy AV Hariyama (Psychic doesn't 2HKO iirc and it doesn't always run Psychic, either) and a few other pokemon, too.
The lack of speed wouldn't he as crippling an issue if it had above average bulk to compensate, like Mega Camerupt, but it has 75/67/95 bulk, which is pitiful on the physical side and a bit above average on the special side, especially with an AV equipped. The problem is that when a pokemon is SR weak in a tier with a lack of convenient hazard removal in comparison to most other metagames (Prinplup is ok, but not the best thing to throw into a team, Claydol is decent and it can run some helpful coverage, but it's no godsend, Mantine is not too hot currently, Pelipper is nice with U-turn and physical bulk, but otherwise underwhelming, etc.), it already has survivability issues. With the vulnerability to physical attacks that Magmortar has, it is even worse.
Generally speaking, for a pokemon to be 'too good' for a tier offensively, it has to have either insane uncounterable offensive capabilities (see: Genesect in OU) or near top-tier offensive capabilities in conjunction with either good speed or bulk, which Magmortar has neither of and it certainly isn't potent enough to fit the former characterization of being uncounterable, either.
With this said, I think the recent suspect fixed the fire "problem" that the tier had and remedied the restriction offensive fires had on team building in the past metagame. I don't think that NU has reached a balance yet, but it is improved from the past meta which is better than MegaLix + Helio meta, so we're working in the right direction for sure (although I'm not too sure if anything else is banworthy or suspect-worthy currently). Hopefully the next tier change won't deprive the tier of anything vital and won't give us anything unreasonable.
