Nobody's asking you to lock in a permanent answer to whether or not it's going to be successful long, but this is a positive indicator. The profitability, even over a span of longer than 3 years, is irrelevant if they can continue to deliver good growth.
If in 3 years time Gamepass is stagnant or has declined in membership notably, that would be far more likely to result in its termination even if it is profitable. Conversely, if it's a billion dollars a year in the red but rapidly growing and emerging as a clear market leader, they are almost certain to continue it. Spencer did not get given a seat at the big table because they want to chase short term profitability, he's put there because they consider it a vital long term interest. They're also doing their best to decouple the success of Xbox as a platform from Xbox as hardware, because that way they are not limited in growth simply by the number of boxes they sell.