I don't think Hamilton will be a one and done, but it's not outside the realm of possibility. If he leaves early, it should mean (should) that he had a monster year and is a potential first round pick. There would be no reason for him to leave without that guarantee after his freshman year. Hard to predict what Purvis will do but the same holds true for him.
Assuming they both are back, for 2015, we would have three perimeter "shooters" in Hamilton, Cassell, and Omar (remember him). Both Purvis and Adams can shoot, but are much more hybrid combo guards who can "score."T-Sam is more of the intangible glue guy, who is working on his shot, but is definitely not yet a shooter. All in all, I don't think a sharpshooter is a necessity, but wouldn't be a bad thing either. I agree that the 2010 team, and really the teams post Denham/Rashard until more recently lacked consistent depth as outside shooters. It was frustrating to watch teams zone us, and see us struggle due to a lack of outside shooting. That's my quick tangent on that..of course there are many variables to consider in constructing a team, including defense, hard work, attitude, etc..not just shooting.