Considering the hard time Columbus had finding support for his travels, what would happen if he never found someone 'desperate' enough to foot the bill, due to their learned scholars tossing his plans for vastly underestimating the distance to travel (seem to remember that scholars allready had a fairly good grasp on the actual size of the earth). Obviously sooner or later Basque or English fishermen would stumble over North America in their cod fishing expedition, but what would change otherwise?