There would be absolutely no reason for Anderson Silva or any top MMA fighter to go into boxing. If they are having success in their own particular field why would they go and try another sport they have experience in?

It's as stupid as Sebastian Vettel announcing that next season he will be driving rally cross instead of Formula one, or Roger Federer swapping tennis for badminton.

There are no active boxers coming over the MMA. It's a last resort thing for those guys, people like James Toney and Ray Mercer who have nowhere to go in boxing and so appear in a couple MMA events that sell out of the novelty factor.

Kimbo Slice has come over the UFC into boxing now. He's currently 3-0 in boxing I believe, though having thought some very weak opposition.

MMA is fast growing sport, and I believe eventually it will overtake boxing as the premier combat sport. It simply has too much momentum and I think most kids walking into gym's in a few years would rather learn a complete fighting system than just specialising in a peculiar gentleman's sport where you fight only with your fists according to strict rules that wouldn't apply in real life.

MMA is much closer to the sport of actual fighting, and therefore likely to be a much appealing skillset to have.

I think the trend will be that more boxers chance their arm in the MMA world than vice versa.