Cynically put, when he is no longer convenient for Putin to keep around.
In another sense - he's a minor warlord, with ~50,000 armed followers, in a huge country. He controls ~zero of the infrastructure, air forces, etc. which would be needed for him to mount even an obviously-doomed bid to topple Putin.
In another sense - he's a minor warlord, with ~50,000 armed followers, in a huge country. He controls ~zero of the infrastructure, air forces, etc. which would be needed for him to mount even an obviously-doomed bid to topple Putin.