As said previously he is still a top player but he is 33 and his body is struggling, lot's of injuries and now unable to play 3 games a week.I'd love to see us hold on to him, if at all possible. With careful management of his playing time, we may be able to get another couple of seasons out of him. However; in these days of FFP, PSR, ABC, XTC etc etc, if a big offer came in for him from a Saudi club, would the club look at it? Also, he's entering the last year of his contract, which is a factor. Get decent money for him now or lose him for nothing next summer, if he doesn't sign a new contract?
He would want a contract extension and on huge wages, again that's a big risk.
He is the one that said he would be interested in going to Saudi, let's not forget that.
IF the Saudi's offered 100m we have a decision to make, that in this market is serious cash, you could go and then make an offer for the likes of Musiala or Wirtz that their clubs would be unable to turn down.