Medlen isn't considered a viable starter option, fwiw (frame, delivery, etc.). He'll come back in the pen, maybe get a shot and make the most of it as a starter, most likely somewhere else. I imagine they have him slated to take over Christian Martinez' role next year.
I did forget Randall Delgado, however. He's considered as good as Teheran, but a bit behind him in development. He should be ready by 2013 though.
All the current starters are signed for next year, and Teheran will be ready. But they still need a CF. JJ is the most likely to be traded. Lowe won't bring anything, and they have the money to pay him next year McLouth and KK off the books. But maybe they'll eat some of Lowe's salary if it'll bring a CF, and keep JJ, but i doubt it. Maybe if we can get the Red Sox and Yanks into a mini bidding war on him. Anyway, one of them is gone after this year, barring injury. Teheran is just too much of a talent to waste in AAA next year. He's Hanson or Heyward level. Gotta clear a spot for him. SS is a question too, but the way AGonz is playing i'd imagine they'd keep him if he'll take the same salary.