The thing about the classic Boxer vs MMA(in a MMA format) discussion is that
1. MMA striking is very different than boxing. There are certain things that just don't directly correlate between boxing and striking(stance/defense/punching style).
2. Most MMA fighters would simply not "box" with a pro fighter. Even if they chose to stand with the boxer you'd see alot of leg kicks and fighting from the clinch(elbows/knees/footstomps).
3. Much like you can't teach someone the science and subtleties of boxing in a few months neither can one master or even become truly competent at takedowns/takedown defense and submissions

I really can't think of a single MMA fighter that would stand a chance against a top 10 boxer in their respective weightclass. But other than a punchers chance I can't think of a single boxer who could win against top MMA fighters.