I've been on MS's Office 365
for a decade since it launched, still the same price today but the value has increased hugely—dozens of extra apps added, dozens of extra usage points [ie users and devices] added, and of course the regular rolling upgrades.
MS has just implemented the first price increase for enterprise users in a decade, so there may be a price increase for consumers sometime soon. It's huge value tho for what you get.
Point being, a large part of MS's 10s success was driven by 365, so my guess is they'll adopt a similar strategy with Game Pass—infrequent small price increases alongside significant increases in value.
There are 3 things to look at with paying for products & services. Price, cost, and value. They are significantly different, but people tend to focus mostly on price—presumably because it's the only one with a number obviously attached. You'll make better financial decisions if you figure in cost and value.