I guess you didn't follow the link to the thread about the many canonical characters who've been killed off in Trek Lit, including other fairly big ones. And no, Shakaar was not a "walk-on," he was a major guest star in three episodes (one of them named for him), was referenced in multiple others, was a pivotal figure in Kira's past, and was the ruler of his entire planet. The last time any Prime-universe series was "active" was -- wow -- nearly seven years ago now. Everything is equally inactive except the Abramsverse, which has no presence at Pocket except in the young-adult books. So no, Janeway is not the exception to the rule, she's the illustration that the old rules no longer apply. CBS Licensing is no longer watching over the books and saying we can't make this major change or that major change. Except where the Abramsverse is concerned, the novels these days pretty much have carte blanche; as long as we don't contradict canon, there's no problem with making major changes, because there aren't going to be any new films or shows in the Prime timeline in the foreseeable future. Depends on the book. If you follow that link I posted previously, and don't mind spoilers, you'll find that two novels have depicted the deaths of lead TOS characters, though only one is in the main Pocket continuity. And Spock was permanently married to Saavik in the novels years ago, although that's in keeping with canon because "Sarek" established that Picard had met Sarek at his son's wedding.