How will they be utilized in 2010? Hard to say. No idea who the coach will be. No idea who the QB will be. (Although, I'd give Campbell an edge over Zorn in their chances of still being here in two years.) Will they still have to compete with Moss for time and Cooley for targets? What will the running game look like? Will it still be good enough to draw 8 men in the box and give the WRs more space?
Those issues, among others, are the reasons talent carries so much more value in dynasty than in redraft. Redraft is heavily skewed towards situation and talent matters less. With Thomas and Kelly, what's important is to watch preseason games to see what kind of NFL talent they have. If they have talent, they will be used come 2010. If they aren't talented enough, they won't be utilized.
As for their talent, I heard Smoot in an interview this morning. He said Thomas reminds him of Anquan Boldin. He was quick to say he wasn't claiming Thomas will be the next Boldin, but he did compare their size and talents. With Kelly, so far I've heard more about him being a good guy than I have about his abilities.