I'm going to go out there and say that Harden probably isn't going to return next year. I think that means that the Cubs are going to get a pitcher either at the deadline (if the bullpen continues it's woefulness, thus adding Marshall back to the 'pen) or during the off-season. From what I've been reading around here and from baseball in general, Peavy seems to be a pitch or two away from season ending injuries to various parts of his arm and elbow. This site in particular has begun to express disinterest in him. So I'm ruling him out.
So the question becomes, who would you get? And what cost would you be willing to spend?
The focal point to the Peavy deal seemed to be Josh Vitters. Sean Marshall was also in that deal but he may be needed next year. So maybe Wells or Adkins is a replacement. Although neither has much major league experience, both would probably get a shot in the majors relatively quickly in a bad system. People have also mentioned Tyler Colvin (who seems like he is finally learning to be a good hitter), Jake Fox, Nate Spears, and Jose Ascanio. Two guys who seem to be mentioned a lot here but I doubt have much trade value are also Bobby Scales and Sam Fuld.I don't consider myself an expert on the Cubs farm system, so I'm sure there are other guys who have some trade value. I'm pretty sure the Shark wouldn't be involved in any trade.
I can come up with a few names for who the Cubs could go after and a few pipe dreams. I'm interested in hearing who you all think they would go after.