Stadia could sell it as an add-on to players which not only don't want to play their games themselves, but also aren't satisfied by watching other people play through their games on YouTube or Twitch. With this add-on, they can finally watch themselves play through their games, without having to lift a finger to, you know, actually play!
Call it Sonic Mnemonic.
Another issue is that machine learning/AI don't predict rare events, like earth quakes. So even with all the knowledge in the world, it won't predict a rare creative move of a player.
I say some but I do believe a large enough volume of data can improve the performance of this class of input/states.
I'm also skeptical about the ability for a model to generate predictions without having too many mispredictions to make it viable.
And those types of game are the ones that are suffering most from input latency.
In a twitch shooter, you mouse over a visible opponent. Would the AI be more likely to pre-emptively pull the trigger for you? Or more likely delay and swing the aim passed the opponent before shooting at air? AKA Is the training set for predictive user actions based on experience of players better or worse at the game than you?