It probably won't be anyone who is already over 2700. Giri is currently the youngest over 2700 at 19, four years younger than Carlsen but there is a striking difference in results.
Remember Carlsen was already playing in Super-GM events at 16 and cracked 2700 before age 17. At 17 he even was #1 in the world for a short time, but it was between official lists and doesn't count for the records, but still . . .
Nakamura hasn't peaked yet, but he can't be too far off at his age. Caruana, Karjakin, Giri, and other young players will also get better, but all the while Carlsen can improve too, and he is roughly 100 points ahead of the field of contenders already. Very unlikely any of them could dethrone him absent some freak circumstances.
When Carlsen loses the title, the odds are it will be to someone who is probably not yet 15 today, but will rocket up into Super-GM status just like he did.
I agree. Its way too soon to start looking for the person who will dethrone Carlsen. I doubt many in 1985 would have picked Kramnik as the one to dethrone Kasparov.
Oh yeah, Rapport. He's got real potential as a top teir player. I think he's gotten stagnant over the last year or so. Kind of like Wesley So & Sam Sevian. The chinese kid Wei might be the next superstar though. He turned 14 6 months ago & he's over 2600 right now.