The other option is if the parliament decides to have early elections which requires opposition parties to vote in that direction too - which they might. The constitution allows him to be a candidate in this case. They might just do it. There are examples of them doing dumb things or maybe they are colluding with him. Who knows.

If he can't run, any other AKP candidate has basically zero chance of being elected.

It's as if they knew their system was fragile, and they can't let any small thing fall out of place, otherwise an immediate danger would be posed.