Game pass doesn't seem terribly popular. Xbox in general isn't doing very well compared to the other consoles. I think they'll keep pushing for games as a service though. It's too tempting to keep all that control out of the hands of players.
It seems fairly popular right now. If you are the kind of person who wants to play many new releases it's a great deal.
But I think it's not particularly sticky: it's a great deal for as long as Microsoft invests into it getting many titles immediately. If they stop doing that, that same audience segment doesn't really have a use for it anymore.
There are logistical challenges that have to be solved, and both upfront and ongoing costs that have to be paid, for every new country that needs to be served, and often these are unlikely to be recouped. If they foreseeably reach 90+% of their potential customer base and revenue (or think so anyway) from those 40 countries then not expanding beyond them is a practical decision that doesn't extrapolate to not caring within those 40.