All for One and One for All theory.
I've been thinking a lot about the theme of the series and honestly think that it will end with either Deku or Shigaraki getting each others quirks.
Alejandro Duma's quote in the Three Musqueteers is "One for all and all for one". The individual has the moral right to protect the colective and the colective has the moral right to protect the individual. The reason the world of MHA is going to shit is because both ideas are too far apart right now. All Might sacrificing himself to save people that does not seem to care about other people is a fake peace at best. All for One using his power to benefit himself just plunges the whole world into chaos. The only way to save the world is by those quirks working together as one.
My guess is that Shigaraki will eventually get One for All, probably because of Deku's own will, and die using it to stop some great evil, either All for One or the quirk singularity concept, becoming the hero he was always ment to be at the end of his live, probably by absorving into himself every single quirk in the world by boosting All for One's quirk snatching ability with One for All.
https://redd.it/otnyru@Boku_No_Hero_Academia_Topic