This was a self-fulfilling prophesy. Google has a deserved reputation for cancelling popular projects so everyone assumed this one would be cancelled as well. The project managers even tried to explain how they were "really, really not going to cancel the service this time, we promise" but people continued to doubt and now it's happened.
In their defense, stadia was a hard sell. Google wanted you to rent your games from them in perpetuity in exchange for not having to buy the latest gaming hardware (though you still needed a fast internet connection). I've been very vocal about never renting software (or even using closed source) but I don't think this view is very widely shared.
Google is now in a situation where no-one will use any of their cloud services because they will eventually shut them down - regardless of their popularity, and any promises they make can be considered a lie. This has been true since they killed google reader.
or so the joke goes, but at this point I wouldn't trust google even if they did bring back reader. What we want is to return to the time when google was an engineering company run by engineers striving to advance the human race. Today google just wants money and will do anything to get it; including tricking people via adware, gaining a browser monopoly and then pushing a plugin model to force people to view ads, and working with the military to kill people.
I believe their "Don't be evil" motto was sincere when it was uttered. I suppose capitalism destroys everything.