It all depends on where you buy your games of course; GOG will let you download DRM-free installers, but if Steam goes down, your libraries goes down with it. They have made a vague promise that they would prevent that if the company ever went out of business, but who knows if they will keep that promise.
Guarantees about playability went out the window the day free, easily-obtained updates came out on PC as much as consoles.
At least on the PC side, there's a vibrant piracy community.