Not at all? You can (indeed, have to) download your purchases from Steam. Many of which are DRM free. Valve has also said they'll remove Valve DRM from the games that use it in the unlikely event they shut down.

There are, in other words, obvious contingency plans.

With this, the game you "own" lives and runs solely on Google's servers. If they decide to shut those servers down, you're fucked.

But good thing Google isn't known for suddenly EOLing popular products, right?