I have an Nvidia Shield Android TV. Perfect for Shooters, race games and other not so complex games. It streams the games in ultra resolution. But it does this only with games which can be processed by a server that can handle that amount of calculations. The console only transforms the signal to a moving image through its Tegra X1 GPU processor. And the amount of games that can be played is limited and besides there is a subscription method where you can play several games for a fixed price per month the newer games need to be bought for ridiculous amounts of money (how can someone ask € 59,99 for a crappy game like No Man's Sky).
However I also can play Steam games if controller is supported. Otherwise I have to connect my wireless keyboard.
I love the concept, but as other people state. When a game like Planet Coaster uses so much CPU power, which shooters, racers and platformers clearly don't need, how can it be efficient.
I can still play Planet Coaster on my "42 inch tv screen but it is then powered by my desktop and transfered through the ethernet cable to the console. So effectively my pc still does all the work. Everybody can do this btw with a long enough HDMI cable.
Latency is definitely not a problem. I play GTA 5 on my tv with no delay while streaming through my Nvidia SHIELD console. It's just that I'm really really bad with controllers....