No confirmation, there have been mentions of places like Chicago as well as others in concept art and the like, but take that with a grain of salt. Either way, the Old Russia map we have is severely cut off, even with everything we have. There are about 4 known areas that we can't access, and I wouldn't be surprised if there were somehow more as well in just the one map.
There are plenty of other areas though. We have seen the smallest of images of Mercury in-game, from a flying ship perspective. Then there is Venus, the Moon, Mars, possibly Titan, and any number of other things. The Ghost itself mentioned in dialogue the word 'moons' for travel, so there are plenty of possibilities. Then the expansions will surely have more. I have also seen some things pertaining to Saturn, and all the other maps will probably be about the same size of Old Russia as well, which is quite big itself.