One's dead and I don't think he's close to the remaining two. His estranged wife has talked about taking over the reins but I thing Silver want's the whole Sterling family out of the NBA so I think he's willing to do the nuclear option and push to have his ownership stripped. Silver's only been in the job a few months and he needs to take a stand early on if he's going to have any control over the owners.
If Sterling transfers ownership to his wife or surviving kids, the NBA can’t do squat. He wouldn’t technically be the owner anymore and thus couldn’t have his ownership stripped.