A sea expansion could add so much more content afterwards, to have more lands to explore...including a land of dinosaurs!
I always thought the Hidden Valley on the Middle level could hold dinosaurs; looks like one is painted on that space;
so another small POD and small alteration and you could have dinosaurs. Example: You have your deck of dinosaurs and primitive type creatures. First person that lands on Hidden Valley places some new marker/token/special card there (which doesn't add to card count). Let's call the card/counter "Hidden Passage". When you encounter, there's a die roll, with a possible result being you draw from the Hidden Valley deck of dinosaurs, etc.
I could envision a number of smaller PODs, some based on the various spaces on outer or middle regions. Mini Decks for Cursed Glade (want to see a Witch Tree card/encounter to go along with the Warlock's Quest which bids a journey to the Glade and the Witch Tree), The Castle ( Court intrigue? Fighting foppish Barons or Dukes? Secret Passages from the Castle to the Dungeon or other spots?, and of course Secrets/objects/powers)