The MS watchers are just speculating, they have no clue about the numbers.
I also don't quite see the difference between sustainability and breaking even. Sustainability means they're making at least as much money as they're spending on 3rd party deals and 1st party game development.
Of course if you include acquisitions, it will likely never "break even", but that's not how you do accounting anyway. Buying an asset for 70 billion dollars doesn't mean that you are 70 billion dollars in the red, after all. It means you spent 70 billion in cash and (ideally) gained at least 70 billion worth of assets.
Sustainability doesn't mean they are profitable. If that's what he meant, why didn't Phil say GP is profitable? I'm sure the shareholders would love to know. Why all the double speak.
They have a plan for the service, a specific growth which in the long term will be profitable. And they will most likely get there. Providing they are growing per plan, it's sustainable. It doesn't mean they are profitable now.
You know for sure it's profitable ('facts') and the other folks like Thurrott and Warren are just speculating, they have no clue about the numbers. Maybe they need to look to you for some quotes.
Edit: I just saw the AXIOS interview who are the ones that did the interview with Spencer. Even they sumarise it as Spencer says is “sustainable” right now. What's with the " ". LOL
Actually ... looking at the entire sentence from AXIOS "I love to see it growing because I see what it does to the diversity of games that people play and the games that we can fund to go create. And I think that's a very magical mix. But its growth is a part of Xbox. It's not the only thing that's growing in Xbox. It's not the only focus of the organization, and it, as a standalone thing, is very sustainable as it sits today, like just today. It's sustainable."
That's sounds to me like he's saying the growth is sustainable ? I could be wrong. More weasel wording from Spencer.