Tuvok was facing neurological health problems due to his advanced age, while that may have not occurred if voyager had gone the “long way”, I expect he would have likely declined command on that basis. Though if it had become known-maybe they could have found ways to slow the disease. But no treatment was very effective in Endgame IIRC.
Seven would assuming she didn’t die-probably get fully integrated into the command structure, and Janeway would probably trust her in that regard once she’d been with voyager a decade or so. I don’t see her becoming captain. I don’t think she’d have wanted the job. She’d likely take on other roles.
I could see Vorik get promoted to B’lanna‘s job.
As for Kim, I don’t see why he wouldn’t get promoted, the only reason he didn’t on voyager was because the positions were pretty much set. It Janeway and Chakotay retired he’d move up quite a few ranks.
I think after fifty years-Naomi, Icheb, and Miral Paris would be leading the ship, Janeway and Chakotay would both be in their eighties to nineties, and Tuvok even if his mind hadn’t degenerated would probably also have withdrawn(though he’d likely still do training and what not-unless his health was declining).
By sixty years, most of the mainline crew would have passed on their jobs to the second generation, they’d still with 24th century technology be relatively healthy, but it wouldn’t be best practice to have a ship run by sixty to ninety year olds.
Assuming the trip took seventy five years, by the time voyager got to earth, you’d have the beginnings of the third generation taking the reigns.
