Stadia was perfectly fine on a technical standpoint. Well, not for VR but still. The main problem is that it also depends on ISPs. As long as they will be slowing down traffic and ramping up prices, nothing about streaming will ever truly take off. That and Google needed to provide a bit more content long-term.^^
VR on the other hand is clearly a future I can see go plain mainstream. Unlike experiments of the past, it's starting to be ready. Understanding of the human brain (sickness in game design) is far enough for it to make good experiences, tech is far enough to offer decent to good graphics, 3D (of course) and wireless VR. And unlock 3D TVs (which should've become the norm instead of a pricy fad...), VR is getting into its second generation with still a bit of steam to go. It "can" become a thing as long as it goes a bit down in price and standardizes itself a bit to make it intuitive for non-tech-savvy people.