Piracy not a thing from pc games?
Then yeah, preserving games will be as problem, but it’s not a Nintendo specific issue.
Say valve goes under, think you’ll still have games accessible?
As far as know, only gog allows for backup.
Some Steam games don’t come with any DRM and function like games on GOG.
https://steam.fandom.com/wiki/List_of_DRM-free_games
It’s a pain to deal with it, just pointing out that there are Steam games that are fully DRM free.