There are a lot of federal holidays that could/should be eliminated.
The only reason I think Columbus Day should remain a federal holiday, at this point, is that eliminating it would be a surrender to the groups that have been demonizing him, protesting at every parade.
But, I don't see why we should add a replacement holiday for a foreigner who had very little to do with the U.S. or the discovery of it at all, like Churchill or Mother Theresa, as important to the world as they might have been.