It's very possible. The power of the hardware today isn't really the problem, the huge amount of paid manhours needed to build the world and content is, it's not really financially clever to spend huge amount of money on developing one game for 10+ years.
Although I guess they could make the game sparsely detailed, like just having one tree and one house for each continent, then they will be able to make it in no time
Using procedural generation for all the content would speed things up quite a bit too.