I'm almost 100% convinced that sooner or later Google will start to turn the thumbscrews on the free tier as well, they are not a charity. Either by annoying you with an increasing number of ads or otherwise mining your data, or by technical restrictions that make it almost impossible to enjoy without upgrading to a paid tier. The most likely end game I see is to apply the YouTube model to Stadia as well. So the question is if and for how long Stadia will have that advantage...