Personally, I don’t think they’d change their personalities much, and they certainly don’t have to swap jobs with each other. Your cutie mark is what you make it to be! Though, I do think it would impact them, of course. SO pardon the simple doodles, but I’ve been thinking about this for a while now! I’ll leave my headcanons under the cut!
Rarity — RD’s talent is… going fast ig, and like,,, trying your best? idk. But in the swap ep, we see that Rarity now has weather magic, which presumably, she didn’t have before. Rarity still sews, but she sees an old love of her calling: theater! She now has this ability to control weather that does not involve physical connection to the elements, so she goes into theater tech work to make the experience more immersive. She ties her hair just for the aesthetics~