If he leaves for less than 30m we make a minusvalenza and the financial benefits of letting Ronaldo go would be significant lower than expected.
After the hundreds of millions of euros we invested, him accepting 50% less money to leave and us making a minusvalenza, while being dumped by one of the all-time greats, would be nothing but humiliating. Add to that that the replacement would almost certainly be underwhelming and there is a strong argument to go the Bayern route of just keeping him, regardless of his wish. Don't think we have the balls to do so though, terrible deal incoming.