One thing I learned from this whole Messi thing is the club don't hold the contracts, but La Liga do. This is why the club even if they wanted to cannot sell him. La Liga see him as too valuable for their international audience just to let go.
The President of Barcelona Football Club is personally responsible for any financial losses incurred during their reign. I never knew that and with no crowds attending matches this guy is screwed and thought would be a good reason to balance the books getting rid of Messi.