That's why I said it's important to try to renew him first. If we manage to do that than we can at least get something for him. If he refuses to renew than he should go to the stands.
We are trying to renew and I don't think he's actually refusing, they're just negotiating and it takes time.
Renewing only to sell him next year could be a risky move as it's quite possible he wouldn't want to leave or if he continues to get injured no team will want to buy him (especially if he'll be injured during/just before transfer windows). So if Laporta will renew him it better be because he still believes in Dembele as a player more than trying make some money by selling him.
But our question here is if it's better to:
a.) let him go for nothing and potentially risk he'll suddenly overcome his injuries (not very likely but possible) and turn into a good player in another club. Don't think he has all that much untapped potential left after missing years of development and his ceilling probably wasn't as high as believed when we've signed him anyway.
b.) renew for let's say 50% pay cut and risk to miss 5-6 months every season when we can sign someone who would play for even lower wages and actually be available for most games (we can't be as stupid/unlucky/cursed/whatever to sign another player as injury prone as Dembele, can we?)?
Not saying whoever his potential replacement would be would turn out a better player/talent than Dembele as he would first need to prove that but would be more useful if just able to stay fit. Would obviously also be a lot cheaper as we can't afford big money transfers now so easier to offload if he wouldn't met expectations.