> Nothing is stopping people

The original game might be stopping people. It's not like games have a good track record of continuing to work for decades. DRM of all kinds poses a huge problem in this regard, but so does garden variety technological change. The GOG preservation team has quite a few videos about deeply technical work they needed to do to make e.g. Prince of Persia run properly on modern PCs. Sure I can just pirate a copy for PS2 and run it with PCSX2, but thats “piracy" (even though I still have a working original disc!).

So, no: there's a lot stopping people, especially copyright law, from keeping around working copies of their games.

> copyright expires

Not in your lifetime. 70 years after death if the author brings us out into centuries. Books written 60 years before my kids were born won't be out if copyright until they are in their 40s, for example.