According to the answer of this question, Columbus was pretty much unique in his belief that the world was small enough and Asia was big enough to make sailing west to Asia possible. Everyone else expected (correctly) that it was WAY too far away to be a practical option.
Of course, it ended up being moot, because there was a completely new landmass in between Europe and Asia: the Americas. Columbus landed there instead, and the rest was history.
But if the Europeans had anything even approaching an accurate idea of how far away Asia was to the west, they must have realized that that would be a COLOSSAL ocean. (About 11,000 miles, we can now estimate.) Did anyone propose the idea that there was more than water out there? That an ocean that big might hold a whole new continent, or even more than one, before you got back around to "India"?
Especially given the Viking discoveries of America (and of Iceland and Greenland), were there rumors or discussions of other lands to the West? Or did the European powers just assume it was empty ocean all the way to Asia, right up until they discovered an enormous landmass blocking their way?