Rise and Fall put the emphasis on Cultural Flipping, not a conquest.
Therefore I think Mongolia could be there on the other side, as an empire which was
challenged by the cultural diversity of its dominions.
Dutch, however, could have William of Orange, as
their liberator, and not simply a colonial power.
Is it really likely that they'll add Venice in two consecutive versions? It is too much of a niche civ.
If already adding Ghana, is a modern leader the best choice?
Quite odd to me. It is not really a prosperous state...
Similar to what I've written to Ornen above you -
I can't see how Genghis Khan has anything to do with this expansion.
A late Mongol Khan is far more relevant, one who's empire has to deal with ethnic diversity and loyalty.
While Kublai Khan is another iconic pick that might fit better, it would be amazing if they add Golden Horde's
Batu Khan.
And Dutch - well, their European existence and William van Orange's career could be the emphasis,
not necessarily the maritime power.
And I don't get it.
Why adding Isabella? It is nearly as ridiculous as Grogo.
It was the same culture and period of Philip II.
If you want a leader for European colonialism:
- Simon Bolivar
- Franciso Pizzaro
- Readjustments of Victoria's personality.
- Charles de Gaulle
- Louis de Buade de Frontenac (some have mentioned the wonder of his name.....)
Well, how about it being a hint for New France's 17th century
Governor of the same name?
Even if the extra 9th leader is not a Mongol, it's no problem.
One later Mongol leader could be added now, while
Genghis may be included in the next expansion.
Who knows, maybe the next expansion will be Horde-based, with Genghis, Atila and Alp Arslan starring the front cover?

Could be interesting to mix with the Emergency.
Whose leader will he be? Mongols? A second Persian?
Having a Muslim Persian leader will be amazing and should have happened long ago in Civ's history.
Either Metternich or Franz Joseph would be absolutely fabulous figures to see on screen!
Both can work with the expansion's guidelines:
- Metternich - counter-nationalism, Flipping and Loyalty issues
- Franz Joseph - WWI system of Alliances, and moreover, first ever appearance of a WWI leader!
But it was part of the Greek world.
Alexander should have been a Greek leader. Instead of the ridiculous choice of Grogo.
One new suggestion -
How about
Bohdan Khmelnytsky of the Cossack Hetmanate?
Ukraine was never represented of course, and it could be a good example of a breakaway state.