For a base game, my 18 are:
2. Aztec (or Inca/Mayan)
3. Coast Salish
5. Tonga (or Hawaii, Samoa, Maori, etc.)
I'd kinda personally been playing with the concept of collapsing tiles into the big tiles, so one settles on the big tile, which then has seven spaces for districts, resource extractions, and wonders, and could expand to adjacent tiles as the game goes on.
Screenshot is less funny, more demonstrating my pain.
I decide to start Small Continents Venice, on a small map.
turn 2, I ask myself "Wouldn't it be funny if Shaka were right next to me"
Turn 8: Meets Attila as well.
Turn 10, from Attila: Hey, wanna declare on Shaka.
Me: Gives up.
So, if they did a final pass, which is seeming unlikely, likely choices seem to be:
Italy for a European DLC, Maybe paired with Ireland, or Switzerland, a Kalmar themed Denmark, or Bulgaria (Or Goths, as I would hope)
Morocco for Africa, maybe paired with an Egyptian alt-leader (Ramesses...