Theory-There will be a Quirkless villain

He would act as an Evil Counterpart for Midoriya. He never had All Might to help motivate him, so he grew envious of superheroes. He would create artificial powers in order to render Quirks obsolete. Basically, he'd be like Syndrome.

• Or, tying in to the previous WMG, he'll somehow acquire "All For One" and go nuts stealing Quirks.
• Given the fact that the manga is partly inspired by Naruto, Midoriya will likely sympathize with a quirk-less villain even if he is forced to stop him at all costs (much like how Naruto sympathized with Gaara due to understanding the pain of being alone and unloved).
• Or he/she will used tactic and technology, becoming an evil version of Batman, which Deku's analytical ability already resemble.
• Alternatively, instead of a Quirkless villain, a Quirkless character may serve as Midoriya's third rival after Bakugo and Todoroki, possibly built around the question What If?, instead of accepting All For One, Midoriya decided to train hard and use tech to become a Quirkless hero. Such a rival would probably dislike Quirk-using heroes and think himself better than anyone who uses a "crutch" like a Quirk, coming off as just like Bakugo if he was the one born Quirkless instead of Midoriya.