If Danny doesn't sign anyone else, I doubt he sends Walker to Europe. As it stands Tony Allen is his only wing off the bench. I'm sure he's thinking that Tony is going to get most of those reserve wing minutes, but he'd be crazy to send Walker away with only oft-injured Tony Allen backing up Pierce and Ray-Ray. The smart move is to keep both rookies around and give both of them a chance to earn some minutes. That's particularly true since Walker has a little more size than Giddens -- if he can be coached up quickly enough, he might be a guy they use to guard some of the bigger threes. I love Tony Allen's defense, but he's just too small to guard a guy like LeBron. Of course, I'm not loving the idea of any rookie guarding LeBron, but...
Walker's recent injury sounded really minor. If he's healthy you can try to play him the same way Philly played Thaddeus Young. Let him play defense and get garbage points off the glass and on the break. Spot up for threes every now and then. He'll miss some rotations, but if he's not a total idiot he can probably be coached up enough that he doesn't kill the team for a few minutes here and there. Giddens, too. They did a good job last year of getting Big Baby in games by keeping his job simple. I don't see why they can't do that for Giddens and/or Walker.