For a moment, I beg some of the naysayers to step back from the troughs of nostalgia and take a critical look at both the Star Wars and Star Trek universes. Now I say these things as an ardent science fiction fan, and a lover of both series, but also as a realist. Neither of these series are sacrosanct or above reproach, any re-imagining should be welcomed and then judged on its own merits, for better or worse. The 'canon' of both series is far from beyond reproach.
Star Wars was a lovely series of films, but let's face it, George Lucas' greatest accomplishment was creating the basis for a universe ripe with possibility. A master storysmith he was not. The plot lines for both the original trilogy and the prequels hardly set the earth on fire, and they certainly weren't anything anyone who'd ever picked up a book hadn't already read a half dozen times. With this in mind, what pray tell is so holy that it must be protected less J.J. Abrams defile it? The man has at least a modicum of story-telling talent (hell Lost's story was beautifully woven up until it hung around for entirely too long and took a sharp turn at the corner of OMGWTFBBQ), give him his moment, let's sit back, consume the media, and then render judgement (you know, while thanking the Fates that we're more concerned about the handling of a fictional universe and not vexed with the ever present worry of where our next meal is coming from.)
Star Trek was a lovely series of television programs and moderately less lovely series of films, but again, it's far from beyond reproach. The show does an excellent job of bringing up a few of the questions that science fiction exists, as a genre, to tackle. It offers them up in 30 minute bite size chunklets, and while this makes for the occasional success, it also make for rather jarring lapses into the nigh idiotically Aesopian. Again, nothing here is all that grand, certainly not something to mourn over should it be tweaked and altered. The notion that Star Trek is 'hard, heavy' sci-fi is laughable at best. That's not to say it doesn't raise a few great questions, no not all. Rather, it's format simply isn't designed to offer real insights into any of the good questions it raises, there's only so much it can do in a television slot (and the films don't do a much better job). Deep socio-political insights in the nature of futuristic civilization? Star Trek is not Dune. A heady exploration of the psychological patterns man inevitably weaves as he colonizes new worlds? Star Trek is not foundation.
Perhaps, we ought to be less concerned with the preservation of these works mythic quality, and focus on how best we mold these universes into venues for new stories, new possibilities.
TL;DR version: Chill, watch it when it comes out, give it a fair shake and judge it on its own merits. Star Wars and Star Trek ain't dat hot shiz no way.