A concern I've heard brought up is if games are no longer supported on a new version of Windows, but steam and steamworks DRM is no longer able to run on an old

A concern I've heard brought up is if games are no longer supported on a new version of Windows, but steam and steamworks DRM is no longer able to run on an old version of Windows that the game is compatible with. Sometimes games like this are removed from the Steam store, like World in Conflict, and can be made to work with some tweaking. But for a decent number of people that can be a problem, and there's no guarantee that will always be possible. To be fair this is dependent on the specific DRM type, if the game receives any kind of fan/official updates to solve the issue, and there's not exactly an easy way out for Valve. Plus games that have to phone in to a central server to work are going to be more of an issue anyway so by comparison Steamworks DRM is doing pretty well.