Updates are planned, and more and more games get longer support periods. Still majority of games stop getting updates within a year.

Every game is different, but for every Subnautica with 5+ years of active development post initial sale you'll get a bunch of successful games and only marginal updates for 2 months.

For my next game, Railgrade, I am planning a couple years of updates, but even that will be dwarfed by the long tail years of continued sales after updates are done. I expect Railgrade to be on the market for 5+ years. For consoles it should be purchase-able for at least a decade until Nintendo shuts down the eShop. Then it should continue being playable for decades more.

At some point emulators will take over and my effort can keep bringing players joy for eons more. I am not interested in Apple's "expiring" model of art.

Railgrade looks very cool, look forward to checking it out.

Games eventually stop getting updates. They're proprietaty software so they're always in danger of becoming incompatible with newer systems. This is true even on Windows: older games regularly fail to work on Windows 10 in my experience and many didn't recover after hunting down the missing DirectX stuff. It's gonna be ironic if Wine becomes the best way to play these games one day.

In a way, this is the whole point of the emulation community. Proprietary software was developed for really old systems and they don't work on modern computers. The old systems had to be emulated as virtual machines on top of which the old software could run.

Maybe for the first year or two, but many many games are pretty much untouched after that, even though there is a long tail of players still buying and playing them.

And yes, many expansions and additional content are usually data-driven, so it might not require a recompile.