From a financial view, you could never rule out a rematch with De La Hoya. I don't think the bout would appeal to the fans, but with the money Manyweather would stand to receive, one couldn't really blame him for taking a rematch.
I'd most like to see Floyd face Cotto if he defeats Hatton. Again, two contrasting styles, personalities, etc.
Mayweather I think would be in a position if he won where he only needs to do career defining fights. He doesn't need to bother with taking out up and comers, only proven articles and the only one left apart from Hatton is Cotto. Hatton will be the Duran to his Leonard and Cotto the Hagler.
If Mayweather beats Hatton it's highly unlikely he'll fight him again, so I don't know what this 'depends on the manner of his victory' crap is. My view is he'll fight whoever gives him the biggest payday. It could be Oscar again or it could be Cotto. I can't see it being someone like Paul Williams.