For other franchises, the clues are more subtle as with the announcement in 2016 of The Battles of Khalkhin-Gol, which was described by the publisher as "the first installment in Days of Wonder's second series of Memoir '44 Battle Maps" — and since you rarely have a first in a series without a second, it was only a question of how long we'd have to wait to see what comes next.
The answer is April 2018 as that's when Days of Wonder will release Through Jungle and Desert, the second installment in the second series of Memoir '44 Battle Maps. Here's an overview of what you'll find in this expansion:
Through Jungle and Desert includes six standard pre-printed scenarios with historical background and special rules, one token punchboard, and two new decks of combat cards: a Jungle Combat Cards deck and a Desert Combat Cards deck. The Jungle's scenarios can be played separately or as a campaign, with each scenario outcome impacting the following one.
To use this expansion, you need at least one copy of Memoir '44 as well as the Pacific Theater and Mediterranean Theater expansions. The publisher also recommends the Terrain Pack and Equipment Pack expansions.