Yeah, I don't think Gerald Wallace will be 'great', but I think he's got a long NBA career ahead of him. And I think Kevin Martin has as much potential as Wallace did when he was with the Kings. The jumpshot seems to be the one flaw that is most easily fixed in the NBA if players commit themselves to working on it. You're right that it seems awfully premature to be speculating on Martin's potential at this point given how little he's played, but that does loom as a factor in this offseason. How badly do we need a new SG? Is Kevin somebody we're willing to trade or is he a future piece of this team? Those are questions that need to be answered this summer so even if there's very little evidence to go from, the speculation is at least justified.
Personally, I think if he commits himself to working on the jumpshot, builds up the strength needed to play in the league, and focuses on his man-to-man defense, he'll be an important part of somebody's NBA roster. He's got the physical tools needed to be a good swingman and he's clearly got some kind of instincts for the game to score that many points on a consistent basis in college (whatever the strength of the competition he was facing). It's really up to him and how committed he is to working on his game. In that respect, I think he's got some good role models on this team and hopefully he'll be working with them over the summer. We'll just have to wait and see.
Oh and regarding Brad Miller (and Mo Evans too), they were draft eligible even if they weren't drafted. I wasn't so much refering to the draft specifically as in 'we have to use or draft picks wisely or we'll fall behind', although that's true too. I just meant that we shouldn't let the desire to fill our holes with proven veterans distract us from developing young talent too.