I'm also in the camp that Shiggy goes too hard too fast and needs to retreat. Otherwise, I don't really see Deku manifesting a singular new power being a dealbreaker here. Black Whip is still something he hasn't really used, with Flight being one of the other known powers. Neither is something I'd call sufficient in stopping him.
What's likely is Endeavor gets the death we expected of All Might long ago. He hasn't been liked as the Number 1 in the world universe and the author has gone out of his way to give him development with Todoroki, the rest of his family, and the inkling he's still trying to become a better hero. However, now that the role of main villain has officially been passed, I'd say Deku's generation is going to need more incentive to step up. Endeavor can be that catalyst for Todoroki. Bakugo has been maturing in his own way now that he's been let in on Deku's secret. Tokiyami had his moment with Hawks. Most of the others haven't really had a standout moment here, but I'm also expecting Ochaco to do something unexpected, perhaps even pulling a Hinata and dying to save Deku, herself. Eraser will survive, but will also be similarly devastated by losing a student.
Pragmatically, something has to happen to delay everything being wiped out. There are still too many unanswered questions for this to really be the end, among them the noted claim that Deku becomes a great hero. I'm actually kind of surprised we haven't had more hero deaths yet, with the only one being Crust jobbing it shortly after his entrance. There's also the matter of OFA likely escaping prison soon, or it being some Aizen tier plan of him wanting to be there all along to release other comparably bad guys. The real carnage is the likely empowerment of villains in the years to come, where the adults we do know will steadily fall or be seriously injured, further mandating the growth of the current gen while Shiggy recovers in the shadows.