It will happen eventually. It's a guarantee. Too much money for them not to make it at some point. Even if Pac loses his next 2 fights and they wait til both Floyd and Manny are using walkers, it will still rake in ungodly PPV money.
Too bad though -- at this point, the fight solves nothing. The only time it mattered is when they were both in their primes. And they're not anymore. So even if Floyd waxes him it will mean jack sheeyat.