Share them by bundling them with DRM[1]? Like archive.org does with books and games that you can't download, but only virtually borrow to watch in your browser (trivial to work around, but it's there nonetheless). DRM-free in a word with current Copyright isn't the solution unless you want to wait 90 years to be able to access anything.
> So if Steam disappears, we're all collectively dependent on our ability to break DRM to maintain our culture accessible.
Piracy has been preserving games since the dawn of time, so yeah, that'll continue as usual. The games that are hard to preserve are the dynamic ones, the MMORPGs that get updates every week and where large parts of the game are the player communities within it, none of which fits neatly into a DRM-free .zip file.
[1] https://help.archive.org/help/borrowing-from-the-lending-lib...