Not only grappling and takedowns. A pure boxer who could fend off all the grappling would eat leg kicks for the rest of the night.
If Saul Alvaerz spent his next 10 years training Jiu Jitsu, Wrestling and Muay Thai, in his physicial condition, he'd be an animal in all three. He'd still be considered a boxer considering that he is 40-0 in boxing and was world champion.
In punch power alone, he'll currently be stronger than every UFC Middleweight. He won't lose his technique or power, but he will gain, in 10 years, great skills in checking leg kicks, grappling and avoiding submissions. A Saul Alavarez with 10 years worth of MMA training under his belt (and still only being 32) would smash the compititon imo.