I think the amount of doping needed to succeed in UFC negates a lot of the advantage of being a D1 wrestler. You can easily dope strength and conditioning (2 of the main advantages D1 wrestlers had). Then if you train kickboxing technique during the years that an athlete is a D1 wrestler and learn how to sprawl, you're going to be at an advantage against a guy who learns striking after wrestling in college until age 24.
So the best base for MMA at this point is probably just any type of striking (muay thai, kickboxing, boxing). Add on doping, and you have a winning combo.