I’ve stumbled upon a way to see what new record collections FamilySearch might soon publish. In the FamilySearch wiki, search for [scheduled to become available] (without the brackets). Then look for titles containing “(FamilySearch Historical Records)” and check the article to see if it contains a header like this:
At the time I wrote this, I found, among others:
Some of these may already be available, but the wiki was not updated. As this is an unofficial way of discovering these collections, I imagine there is no guarantee of when, or even if, FamilySearch will get the collection published.