And if it ends up in Court they will lose. No club wants to be the losing club that establishes the precedent, that will be super expensive. So when push comes to shove - and it hasn't yet - they will give in. That is why there is so much posturing, "We will never", "It's not going to happen", "He's not for sale", but in the end they always give in.
I suspect the precedent will be set in Europe, and then we will all be in a different place for contracts and transfers. The current system of loan players is especially vulnerable. When it comes to Court they will almost certainly decide that if the player wants to stay at his loan club, then he can. The FA might set up an arbitration of compensation, but that would be between the FA and the clubs, it would have to be structured so it didn't stop the player. That would be a good thing IMHO.