Good post but do you really think Dembele is that talented? I think there is no area in which he's better than Mbappe while his weaknesses are much more significant, especially first touch, close control, passing and decision making.
I think there are many players in this generation +/- 3 years who are more talented and better competition for Kylian in 3-5 years. Sane, Pulisic, Asensio, Dybala and Sterling are the first thoughts. Personally, I'd take many others over Dembele as long as we are only talking about talent, too, since I think they have greater potential: Sancho, Foden, Diaz, Havertz, Brandt, Martial, Rashford, Coman, Malcom, Bernardo Silva, Jesus, Vinicius Junior and Rodrygo all look much more comfortable on the ball if you ask me. The only thing they lack is Dembele's crazy speed (although being extremely quick in their own right) but when we look at the last generation, the fastest weren't the ones that came out on top.