[Sarah Bernardini]

Obviously the next decade will probably have Sinner vs Alcaraz but there are young players like Shelton, Rune and Fils that have the athleticism to rise to the top, but  they are still lacking on the mental side.

Fonseca, Engel and Landaluce are very promising but still too young to have a chance.
My longshot would be Diego Dedura Palomero, I've been watching him irl for quite a while and he seems the real deal.