I registered just to answer this topic.
About Italy: as someone already said multiple times, pre-1861 Italy was a cosmos of states, duchies, counties, etc. I can't really see something like post-1861 Italy ingame, as this would imply Rome as capitol and multiple CS would be redundant (not that some of them already are, they could just "fix" this by PRGing only CS not linked to in-play civs).
I place my bet on one of the main "partial" states composing Italy: Savoy (Turin, Corsica, Sardinia), Kingdom of Sicily (Naples, Palermo, Sardinia - they're less far away from Africa for scenarios too), Venice (itself, Zagreb, Iraklion and some of the balcanic coastal cities). I tend to exclude Florence: their land was too little to be implied as a civ (like Switzerland for example) and Lorenzo was already "spent" in the intro video of GK (yeah, that's Florence).
About the other civs: except the already known ones (Poland, Portugal, Zulu, Brazil, Assyria) and adding one of the italian-flavoured, I place my bet on Inuit (interesting choice IMO) as the only new American civ, plus an Asian (Vijayanagara or Indonesia) and another African one (maybe South Africa with Mandela?
).