The thread title could mean:
A) what units I would like to see in the next unit previews
B) what units I hope to see implemented in the game, that might very well be left out

I assume the answer is B...

Vlastlela cavalry (Serbian "knights")
Norman knights
Almughavars
Flemish militiamen, preferably in both pike and goedendag flavour
Huskarles (not the odd looking axemen CA decided to name "huscarls")
Italian knights (Italian cities didn't have "Gothic" knights, they used "Milan" style armour")

One that I have mixed feelings about is the Hashisin unit from MTW. They should have just been assasins, but in the game they essentially were battlefield ninjas. If they're in they should be named "Fedayhin" or something similar.