He had an option to leave for free if he informed the club by May, but is apparently trying to argue because of covid and the extended season that should still apply. I don’t think that flies at all, if the date is in the contract then that is that I don’t see any way at all he wins that in court.
If barca do let him go for free, and if he just wants to play for Pep again without demanding too much wages, maybe it is doable. But it still **** the long term plan for a couple of years of possible short term glory.
I would still prefere the plan to be challenging to bring in the likes of Hangerland and Upamecano rather than a Messi swan song.