Three of them don’t need to change much, really:
Mako is still a cop. There’s absolutely no reason to change that. XD
Bolin is an entertainer of some sort, probably either an actor or a comedian.
Asami is an executive in her father’s giant multinational technology corporation and on fast track to becoming CEO when he retires.
…and that leaves Korra, whose Avatarverse job really doesn’t translate over very well. XD;
I could see Korra being any number of things, all of which are extreme in one way or another — special forces in the military, professional MMA fighter, extreme athlete (snowboarder, rock climber, surfer), etc. She’d probably be the sort of person to train for intensive athletic competitions like Ultimate Ninja Warrior and Ironman Triathalon-type races, too.