I don't think Trent or Lee expect to ever be fantastic NBA players, there are lots of players in the NBA that come off the bench occassionaly and make lots of money. The money is a big motivator and why stay in college for another year if an NBA team would take you now? You risk injury, a down year, and you miss out on one year of making a lot of money. Besides you can develop your game in the NBA just like you can in college.
Having said that I think both players will be back. Lee is playing better than anyone else on the team right now but I still don't think he is as great of a pro prospect as Trent. 2 guards are a dime a dozen so I think he will stick around for sure. Trent is still questionable, after Louisville and UNC it was a sure bet, then after UNLV and utah it was a sure bet no. Now he is playing somewhere in the middle. If a team is willing to take either of these players they would be stupid not to jump at the chance.