The only demographic that matters in the long run is the youngest demographic, and that demographic is the most likely to own/use very underpowered hardware (Since they don't have their own money to spend on nicer hardware. Often they use hardware issued to them by their schools, or hand-me-down hardware from older siblings or their parents.) The specific implementations of Stadia/etc may not prove successful, but eventually I expect a service like this to overtake the alternatives for very young users, and subsequently, achieve dominance when those young users come to view those services as normal and familiar.