The BO clause + a WC player like Di Maria? Adn you reject only to make them pay more taxes? LOL. This may resonate well with fans but it's bad business from Barça. Delaying this will only hurt the team even more.
Is Barça willing to waste one year of a prime Messi? If so, then do it. Fights, leaks, and other bad things will only increase if they try to force Neymar to stay.
"Oh, but this is a WC year". His spot is secured. Brazilian players don't care about legacy and all that crap. Most of them grew poor as fuck, they couldn't care less about 1st world things like 'legacy'. They play for fun and for money, very little else. He wouldn't have any in Barcelona.
If it's necessary he may even score an own goal in El Classico.