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!
APPLE JACK — Rarity’s cutie mark represents her inspiration and creativity, not that she can sew! Apple Jack would still very much work the farm, still living with her family! She just now has a new hobby. She now does sculptures from dead tree’s wood and incorporates gemstones into them. And they are GIANT. Her main method for carving is bucking off pieces. She cut her hair shorter because she was tired of having so many splinters and debris getting caught in her hair all the time (and just cus I think it’s cute!)