This is chock full of wishful thinking. Adam Dunn isn't going to take a psuedo-part-time job to "showcase" his talents for a future contract. His talent level has been established over the last 8 years. Furthermore, the market probably hasn't hit bottom yet. Entertainment lags industry, so next year's FA market is likely to be worse than this one. His best bet is to take a deal of moderate length to bridge the gap to a recovered market. Finally, the best remaining offensive players seem to be playing a game of chicken where they wait out the other guys in an attempt to be the "best option left" who can take advantage of last minute desperation. The last point is just IMO.
EDIT: Oh, and that's before we look at spot for him. Mark Teixeira is orders of magnitude better than Mike Lowell, so you make that kind of pick-up and trade Lowell, and playing time is easy to figure out. Dunn is closer to a zero-sum tradeoff with Lowell due to his defensive deficiencies. Yes, he provides depth, but 1) I don't imagine he cares one bit about the Sox depth if he's riding pine occaissionally, and 2) he won't come as cheap as some are suggesting.