No chance of that.
Milan wouldn't come anywhere near the pay he's getting to play in MLS. Second, MLS wouldn't sell him unless Milan comes in with some stupid transfer fee (think 15-20M+) which they won't as he isn't worth that, even from a marketing standpoint.
If Milan were crazy enough to offer stupid money for him, MLS might be tempted to cash in.
But, as it stands, he'll be back in time for the LA Galaxy season opener in April 2009. In the meantime, he can stay fit, stay in Capello's plans, get a few appearances for Milan, and continue marketing Brand Beckham.