Let's take a look at some numbers of input lag measured
by Digital Foundry.
Last gen, Modern Warfare 2 on PS3 measured at 77.5ms of input lag. We all agree that Modern Warfare 2 had quite responsive controls, yeah? I mean that's basically Call of Duty's claim to fame: it felt incredibly responsive.
This gen, Modern Warfare remastered is clocking in at 39.3ms of lag. Toss it on Stadia with 35ms of network latency and it'll still be more responsive that last gen's Modern Warfare 2.
Arstechnica was measuring Halo 5 coming in at 67ms on XCloud.
My point of the comparison is simply to show that streaming games could feel plenty responsive. No, streaming is not better than native, but it could be perfectly playable.