They had to release the cast. You can’t keep cast members on a contract indefinitely for the rest of time. Netflix have done nothing wrong in this scenario.

And from interviews I think the cast would be open to returning if season 3 happens. It’s Fincher after all.

They didn’t let it die. They are willing to do a third season but fincher is very busy so they are waiting on him. It’s his baby so are not gonna do it without him.