A 3rd expansion would be nice, or at least some stand alone civs as DLC.
I would still like to see the following leaders / civs added to Civ VI.
Martin Luther (alternate leader for the Holy Roman Empire / Germany)
Charles Lindbergh (alternate leader for America)
Jean Sibelius (Finland)
Charles Martel (Frankish Empire or alternate French leader)
Jean-Baptiste Colbert (alternate leader for France) (was Finance minister for King Louis and advocated Laissez-faire Economics)
Rollo of Normandy (Normans)
Since Prussia is not featured in the game, perhaps the Teutonic Order could be added to the game in place of Prussia? They could also try adding the Hanseatic league.
If there was a Mount Rushmore for Western Civilization, I would put Martel, Luther, Colbert, Sibelius and Lindbergh on it, as five of the most important figures in western history.