I knew Thompson was DFA before the Japan trip but yes I also did not realize he stayed in the Cubs organization. Maybe he pitches well enough to get back on the 40 man at some point but I would guess if he gets another chance in Chicago he's going to have to pitch well enough to stick around else he will be DFA once again when there is a roster crunch. At times he's looked really good but between sometimes hurt and terribly inconsistent he ran out of chances and they had no choice without minor league options left.
I took a look at the I-Cubs stats so far and I agree, Wicks is going to need to pitch better before he gets another chance in Chicago. Really would not hurt my feelings if they included him in a trade at some point as I don't think he's ever going to be much more than a fringe 5th starter type of guy if he can stay healthy. As far as pitching at Iowa goes Chris Flexen is a guy to keep an eye on because he probably has some kind of opt out in his contract at some point so if he keeps pitching well would not be surprised if he opts out to find a better situation if he's not called up by then. That was the same issue they had with Keller who they added to the 40 man to start the season. Keller apparently had an earlier opt out and he pitched well enough in spring training they didn't want to risk losing him. So far I think that was the right move, he's pitched about as well as anyone in the pen so far and is someone that can throw more than 1 inning too.
For other pitchers on the 40 man Palencia and Little will likely be the next arms up in the bullpen at some point. Both have a lot of upside if they can stay healthy and locate their pitches consistently. Horton should be up at some point but there is no rush as need to make sure he stays healthy and is dominating the AAA level to the point where he's not being challenged anymore.