If I'm sending AD to Pittsburgh (which I would if Donald wants out; might as well let him go to his hometown team, right?), I'd ask for their first and the second they got from the Bears. That's basically two first round picks (since Miami's owner's idiocy makes Billy Madison look like Albert Einstein), which I think is a fair and realistic price for an elite player past thirty.
Would it suck to lose AD? Sure. But I think we're undergoing a slight rebuild as it is (with the scuttlebutt of trading Ramsey, Robinson, and trading/cutting Floyd, and I have to imagine that Allen's gone as well, so we'll need a center.), along with free agency.
This is not going to be a competitive team next year, unless we hit on most of the draft picks, re-sign our key players in Gay and Gaines, get our key players fully healthy (A-Jax comes to mind.), and have Lady Luck on our side.
Fortunately, we have the right people to do that. That's what's most important: having the right people to propel us back to greatness.