I don't think the Cubs' trade landscape will start to take shape after the Super 2 time period is up. I expect another influx of talent soon from the minors. Arismendy Alcantara is torching the ball right now, and if he starts to draw some more walks (he's only drawn 2 so far), Darwin Barney becomes totally expendable with Bonifacio, Valbuena and even Lake all capable of playing second. Logan Watkins (also a second baseman) and Matt Szczur have shown discipline at the plate. Both guys offer speed on the basepaths and Szczur is good enough defensively to have value at the major league level with that skill set alone.
I'm totally against dealing Samardzija at this point. Ditto for Wood. And honestly, if Hammel keeps pitching like this, I'd really like the Cubs to try and extend him as well. Kyle Hendricks should get a look later this year, so hopefully that pushes Carlos V completely out of the rotation and lets Edwin Jackson slide down another peg. The starting rotation has some substance. Grimm and Rondon have both looked solid. Strop has had his hiccups, but I still think he's a guy that needs to stay. Pieces are starting to fall into place, the huge glaring need is still lineup protection for Rizzo and Castro.
So -- in terms of "likeliest to get dealt", I've got Barney, Schierholtz, Samardzija, Villaneuva, Hammel and Veras, in that order.