Comment by dark-star

No. At least in some countries (e.g. Germany) they would be forced to reimburse every buyer if they removed access to a game someone bought.

The fact that somewhere deep down in their EULA there might be words that make it clear that you're not really "buying" anything, just renting/leasing/whatever, wouldn't stand in court since the important part is the big shiny "Buy now" button, and "buying" has a specific meaning here.

So yeah, the only way they could "take the games away from you" is if Steam went bancrupt