They still have to pay for the service and Lord knows how much that will be. Of course, there will be tons of people who don't have access to the speeds or high data caps to get a good experience from game streaming. In those cases, local HW is the only option. There are also people like me who will not want to put up with the compression that comes with game streaming and will want to take full advantage of their 4K TV.
Also , when Phil Harison said "open free Internet " in the Stadia reveal conference he forgot that Internet it self is not free, far from freedom and limited by country law, and bound by politic, censor policy and monopoly by ISP.
People will not let their favorite games hobby and life, bound by others peoples will . Normal people who is not crazy will not pay and let them self bound by that kind of rule. There will be more people pay for freedom of owning games , rather then just renting and ruled by others people will.
Renting will just be renting, but others will just buy games and owning the games. Streaming will just another renting that will not replace or even on par with buying your own games and console/PC. This is just pure fact from the moment the world is created until the end of times. This just basic economy.