The number of people who read books by major SF authors is pretty darn small compared to the number of people who go to see big Hollywood movies. It wouldn't have all that much of an impact.
More important, though, is that the book has to be on the shelves when the movie comes out, but the studios reportedly release the scripts to publishers at the last minute possible these days, to avoid leaks. You may be able to convince a big name to write a Trek novelization, you may even be able to pay a hell of a lot more than the usual Trek novel pay rate to match what the big names usually get for their books, bu the question is whether you can get one of the big names to write up to their usual standards and still get a manuscript done in a matter of a few weeks instead of months or years.
I don't have any inside info, so I could be way offbase, but it doesn't seem terribly likely.
Let me guess and say: no chance in hell it'd be Gerrold, and not much chance it'd be Carey, who's gone off to do other things.
