Deku will unlock all for one's quirk stealing ability due to the fact that one for all stockpiles power as we recently seen in the anime and we already know in the manga deku is unlocking the corks of the previous OFA users And he only has one left to be revealed from the other users

However remember all for one had the stockpiling quirk before he gave it to his younger brother And during that time that AFO held it there is a possibility that it was able to copy the quirk stealing ability and as one for all has grown stronger over the generations it will be the last ability that one for all will unlock only it will be far more powerful whereas the original quirk stealing ability requires touch in order to steal theoretically the augmented version could steal quirks just by thought or proximity

I would like to see other people's take on this because theories are a great way to discuss the community.