Yes Stastny's line would be more productive with an upgrade at RW. No, its probably not going to happen soon. The cap space needs to accumulate so that a deadline rental can be obtained with futures without parting with anyone off the roster (OK, maybe someone like Paajarvi). Stastny needs to play better, but he still has PP time to show improved production too.
Berglund is playing very well right now. If he hadn't had a couple posts in recent games, he could very well be on a scoring spree. I think its coming, he just needs to keep it up. I'm not a fan of trading him at the moment, but I think he's going to be gone in the off-season. Trading him for an upgrade at wing still leaves Lindstrom/Paajarvi as the other wing, which is a problem.
SOB needs to be kept intact and let the Stastny line just do whatever it can manage to do. Don't fixate on his numbers. Steen and Oshie finally are starting to play better when they're getting consistent time back with a line that has known chemistry. The STL line also has tremendous chemistry. I say just let the chips fall and don't hand-wring about Stastny's salary. He'll be important in the post-season, and with an upgrade at wing (a shooter) that line could become a serious threat. Meanwhile, the team can win a lot of games with what they have right now.