Well, sometimes you have space constraints. The O(n) extra-space required by mergesort isn't always available. But if you don't have space constraints, mergesort is a very good choice because you can easily write a highly scalable parallel version of the algorithm.
I think that probably it will get out of stock quickly. It's a marketing move that gets reported by major news sites, and raises interest among non-tech people. If everything goes smoothly, probably it will get less coverage.
Conflict resolution is not very sofisticated. You can choose to always take server side version (the default) or client side version (see https://github.com/astrada/google-drive-ocamlfuse/wiki/Confi...). My main use case is a single user working on the client or on the server. So the scenario is not of a collaborative app.
In Italy it isn't popular at all, but a couple of friends of mine use OCaml, mostly for hobby projects. And I like the language. It is more advanced than main stream languages I know (C#, Javascript), but, being strict, it is easier (for me) to reason about than Haskell.