Difficult one isn't it, the situation right now is so unique.
On one hand you've got possibly the greatest footballer of all time who is seen as a god at the Club for what he's done over the past decade. He's the difference right now to the side being poor and competitive, so no one in their right mind would want him to leave, but...
... on the other hand you've got a board who are running the Club into the ground, and this once in a lifetime player could potentially have the rest of his career ruined by the Club he helped have one of their best ever periods in its own history.
I wouldn't begrudge him moving on. It would take an almight fee to prize him away, but IMO he should be thinking about it. If this was Ronaldinho in his prime i'd be dead against it... but it's Messi. He deserves so much better.