Clearly worldwide payments
is an issue otherwise they’d have rolled it out worldwide day one, and they didn’t. There must be something holding that back.
Plus I really don’t think you can compare B2B payments for premium API access to end user payments. Not least because they aren’t going to be going the same route: a huge number of them will be via Apple or Google in-app purchasing. Ask anyone who works with those systems, it isn’t a quick plug and play job.
In general though, a new subscription tier, feed algorithm changes, UI changes… if these aren’t, what is a big change in your book?