Also, when those other streaming services are at least somewhat established there will most likely be content fragmentation soon after, i.e. Microsoft (published) games only on "Project xCloud" etc. like we're seeing in Video Streaming currently.
That's been the norm of the gaming industry for ages. Mario, Sonic, Halo, etc - its always been fragmented. You have to pay for an expensive console to get at the exclusives.
Streaming services have the potential to improve that situation - assuming most are easy to subscribe/unsubscribe as video streaming services.
That was also the case with video streaming. Unfortunately once the publishers/broadcasters got the faintest whiff they could force customers into paying them a subscription fee for their content (and after that some services have the audacity to still put ads in/on/around the content) it was every publisher for themselves pulling their content from competing services' catalogs (like IIRC Disney pulling all their stuff from Netflix).
I can already see this coming once the competing publishers have all set up their own GaaS solutions.
But even so, with the fragmentation in video streaming, its far better than it was to be locked into a single cable provider. Likewise, game streaming will be better than our present situation, where to get that one exclusive you really want to play, you have to buy the whole console. In the streaming world, you subscribe for a month or two, then suspend the subscription.
The battle in the streaming era is going to be over reducing churn, rather than finding the right combo of exclusives to entice enough people to buy the console, even though they might only buy a couple of games for it.
I think we'll start seeing episodic style exclusive content.
This is pretty much it. Google is fundamentally an advertisement company and that scares me.
I disagree that the reviewers lacked long term vision. Nearly all of seem to have been burned by the promise of videogame streaming before, and the current state of Stadia only inspires cautious optimism at best.
You're right that everybody wants to live in a world where videogames stream anywhere at 4k+ and 60+fps with minimal latency. But OnLive was 2010. Gaikai was 2012, followed by Playstation Now in 2014. This space isn't a greenfield for lack of trying.
Furthermore, with initiatives by Microsoft (Project xCloud) and EA (Project Atlas), there's no reason to accept Google as the standard bearer for game streaming. There's plenty of companies that could be coming up with the experience we've been waiting a better part of a decade for.