Considering there are tons of games that are no longer supported, the answer is yes, the game customer is left to the elements when the publisher decides they're done. And with the current DMCA, we're not even legally allowed to break DRM for legal purposes (such as to play games we bought when the DRM is no longer supported.)

Curiously, it does send a message for the determined end user that legality is only for suckers (or for companies who have to operate within the constraints of licensing). Curiously, Windows 10 and 11 depend on the ignorance of upper management regarding the degree to which Microsoft has surveillance access, since companies don't get to medium-sized without having a few skeletons in the accounting closet. I'm surprised so few companies haven't switched to Linux Red Hat (which has a similar support package) but then Red Hat is going through its own scandals right now.

Anyway, if your game is popular, you can expect the old version to be supported until the redux comes out. If it's a niche game produced by a company that the publisher bought a while ago and would like to forget, yes, it'll disappear into the aether as you watch.