Brainstorming a Point of Divergence

I had tweeted:
Given where it sends me, if Chris Columbus had my Garmin, he would have wound up in Istanbul
Chris Columbus left Palos de la Frontera on August 3,1492.
Not surprisingly, there were a couple of comments saying that it would have been better if Columbus hadn’t reached the New World.
But how plausible is it that Europe would not have reached the Americas sometime within the next 30 years? If it wasn’t Columbus, someone else would have tried the western route, and soon. The economic pressures were too strong not to try it.
So, how far back in history do you have to go to make an Old World where Europe is NOT striving westward in search of routes to the Orient? And what is your change to make it plausible that 15th century Europe doesn’t come into contact with the Americas?