I think that if Nicole Janeway had been written with some of the same badassery as Kathryn, it might have been interesting to see an older lady kicking ass and taking names across the Delta Quadrant. (Boy, think about the uphill battle she would have had for acceptance. "She shouldn't have a gun! She should be sitting around knitting!")
Obviously, Bujold did not do well in the role, but, if she had clicked with the character, I think it might have been a bit of an interesting ride.
Not as interesting as Admiral Janeway on VOY would have
(The endgame one.. easily as old as Bujold but.. so.. much.. more.)