spoilers:end of spoilers
Yeah, I've been seeing alot of those arguments too about Iron Might breaking the whole notion about being a Quirkless hero. If this is done in how we assume it'll be, basically just acting as a reckless distraction without actually being able to successfully harm or contain him, then yeah it's perfectly fine.
Also Izuku's whole question about "Can I be a hero without a Quirk?" is basically answered in that chapter as being the distinction of Hero and "Hero". To be the type of Pro Hero Izuku dreams of being, yes he does need a Quirk. But to just simply be a "Hero", doing good in the face of adversary no matter what, no he doesn't, anyone can do it, which is what Izuku proves to him in that first chapter, and now All Might is showing off here. He may not necessarily be able to "save and win" the day right now, but he's definitely still acting as a hero.
spoilers:spoilers:end of spoilers
I can absolutely see this leading up to Deku's big declaration as he saves All Might from a raging AFO as Shigaraki comes in with his own twisted version. Getting all four of them in one spot would be great. end of spoilers
Having all four of them together makes the most sense, but I'm curious how that would go about. Since we know Shigaraki hates All Might just as much as AFO, so it would basically be three people he wants to kill all together, and cause I still believe the most obvious outcome should be Deku and Shigaraki fighting AFO together, AM would probably have to be taken out of the equation at some point. On the other hand, having All Might get the chance to say everything's he wanted to say to him since learning he's Nana's grandson would also be a very important thing to include.
spoilers:end of spoilers
Yeah this seems to be the best conclusion to his arc, Dabi having some emotional conclusion with the rest of his family, making peace and instead of exploding in a giant nuclear blast, calmly dying and probably just fading to ash in something dramatic like that. They've been hammering home how destroyed his body is for so long that honestly it's hard to think of a way he could completely survive without it feeling cheap.