There is no loyalty in football generally, though there are some exceptional cases - Scholes, Giggs, Neville. Notice a common theme with those 3?
Football is an unpleasant business where money rules.
But besides that, let's just acknowledge that for as long as I can remember in his short career, Ronaldo has expressed a desire to play for Madrid. That should tell us all that he has no intention of doing a Scholes with us. He will be off, it's just a matter of when, but as he's won it all with United then it would seem that now is ideal as far as he is concerned.
His value is as high as it will ever get, unless he ends up top scorer in Euro 2008, but even then, paying in excess of 100m is unlikely whichever club eventually buys him, despite the fact that Madrid (or whomever he joins - lol) will probably recoup that in a matter of 2 seasons thanks to merchandising sales.
So let's just say that Ronaldo has his heart set on a move to Madrid one day. As far as I am concerned, his heart isn't in playing for United anymore, if it ever was at all.
Back to money, he will also of course earn the fattest contract in world football if he goes to Madrid and that will tip it all in their favour as we will not be held to ransom by the player or at least will not want to look like we caved in to him just a year or less after giving him his current fat contract.
I say sell him for as much as we can - let there be a bidding war between Barca and Madrid and accept the highest offer. It will be Madrid eventually because he doesn't really want to play at Barca.
We are just a stepping stone to where he wants to be frankly. And I don't care what anyone says, Madrid probably are the biggest name there is in world football, yes, bigger than United. We will be bigger than them when we build a dynasty that wins 3 CLs. Shame that he wants to go, because we would have done that with him, but just because he's off, doesn't mean we still can't.