They will stretch out announcements over the course of the next months or so, probably with a Chronicles hitting the shelves a week prior to Thanksgiving, Strongholds hitting just in time for Black Friday, and then Keeping the Peace timed to release with the TFA release. Or in some variation of that order based on how projections for which book will sell the best being the last one released.
Or at least, thats what I'd do.
EDIT: Also realize the Asmodee merger, took place last year, so I doubt that has anything to do with the release schedule as FFG has been operating as a member of their group for awhile now.
Edited by BigSpoon