Ugg, it's reading spoilers that this that make me wish I'd remained spoiler free . . . I mean, it could turn out well, it could turn out horrible, but we just don't know!!
But I think it's entirely possible that Syd was with some other guy after Vaughn; maybe Vaughn is in a coma for six months and she went for some comfort, or maybe Vaughn came out of the crash okay and told her the truth and she got so upset she punished him by being with another guy.
The idea of them permanently seperated is pretty painful . . . but maybe they are just trying yet another way of keeping them apart . . .
And I'm not sure how I feel about this "young protoge" thing . . . but then again, maybe this is a way to potentially let Alias continue w/o Garner? If the new character really takes off, then she could become the focus as Syd takes time off for maternity leave.