Don't forget that WASPs often excluded entire professions to what they considered 'lesser' whites and catholics and Jews.

Ben Shapiro once said that Jews might not be good at the NBA like blacks when he doesn't realize (or does but is lying) that Jews dominated basketball in the 1920s and 1930s. Ironically then as now racism played a role in stereotyping them. Since Jews were seen as crafty and intelligently sneaky this was seen as manifesting in the sport, which often does need deception to get ahead.

They could go further back and not count the Irish either

The concept of whiteness comes from the Spanish inquisition after the fall of Grenada. Being fair skinned was a way of proving without a doubt that you weren't a jew or a muslim.

My guess is we'd start dividing up amongst religious heritage again. Mormons vs. Evangelicals Vs. Protestants Vs. Catholics Vs. The Real Christians

Well the Irish would not be white again.