If someone is going to disconnect Russia from Internet it is going to be Russian themselves, to limit the free flow of information that might be conflicting with the official truth.
But like with the Chinese firewall, information find its way. Unless Russia wants to set itself back to 70s, they still need to access Github, Cloudflare, Amazon Cloudfront, etc. For the Russian IT business to work. It is going to be very inefficient to run anything with a pen and a paper.
Software development and Internet were built on scientific principles, criticism, criticial thinking. This requires free flow of information. You cannot have one without the other, or you are going to end up with very inferior and inefficient software ecosystem.