I've got to agree with Cassandra on Lupin, I think he just has to be at Oxford. And I like your take on Sirius, Cass; I trust you to know him best. I don't think Lupin's in France, but I do think he has some French cousins who have a vineyard and make some very good and well-loved Wizard wines.
Ludo Bagman would be a TV sports commentator (and compulsive gambler - some things stay the same). He would also be doing commercials for those 10-10-whatever long-distance plans (the 'hey, look, I found a dollar! ones). I actually had an in-HP-context idea of Ludo doing print adverts for my Mrs. Moffatt's Magic Meals - "So simple, even I can do it!"
Arthur Weasley would own a big electronics store - lots of Plugs and eckeltriptic appliances.
Rita Skeeter would be a talking head on all the 24-hour news channels every time a scandal broke.
Gilderoy Lockhart would be a self-help guru who goes around giving seminars at $250 a head and autographing his (ghost written) books for his adoring fans.
Well, those are a few I don't think have been mentioned yet.
I don't think Lupin's in France, but I do think he has some French cousins who have a vineyard and make some very good and well-loved Wizard wines.