Even then, I wonder why would Google choose a gTLD over any other TLD. For Google, content only matters. It doesn't matter what your address is. If your meal (content) is good, then spidey is happy to munch it and send it's recommendations (traffic).
I could imagine google giving higher priority to .book addresses, provided that (a) the user was searching for a book and (b) .book addresses required that the registrant prove that they're the author/owner of a book/book series.
In that case, it'd make sense to. I think Google thinks that way with domain names as well.