If the company is going bust then the last thing their shareholders are going to do is let them pay devs to do stuff that doesn’t make money.
So, realistically someone would make a tool to do this automatically (not done now because API changes quickly, which is not an issue at EOL).
The larger issue is multiplayer servers run by Valve. Some games allow you to run a server and connect to arbitrary servers, most do not. Those are going to be somewhat unplayable without explicit action from Valve.