Well that's the obvious assumption, which is why we haven't heard anything. I guess it'll come down to how much EON really wants to break formula and try something new.
Well, I thought it was important to stress the rumour part because I cannot think of a subject that is more polarising among fans than the identity of the film's composer. I didn't want people latching onto this as proof positive of Newman's involvement - especially if it doesn't pan out.
The importance of the musical score cannot be understated, it's imperative they get the right person for the job.
Of course. The first thing I teach my students when doing a film unit is that sound is the single most important tool at the film-maker's disposal, because it provides the audience with emotional cues.
You think they would ask Newman to submit some samples before committing to him?
Assuming for the moment that both EON and Newman are interested, I think a lot will come down to how they view the project. Some composers like to score straight from the script; I seem to recall reading that Hans Zimmer knew he wanted a Renzor-style industrial vibe for the Joker in THE DARK KNIGHT before he had even seen a frame from the film. By comparison, that distinctive "BOW ... BOW ... BOW" sound in INCEPTION is actually the Edith Pilaf song (that the character use to warn one another that they're about to wake up) slowed right down to be at the same speed as the characters would hear it in the bottom level of the dream. That obviously took some planning.
I'm not really familiar with Newman's work, so I can't say for sure - but a lot will come down to how EON want the film scored and whether Newman's ideas line up with that. For example, one of the complaints I've heard about Arnold is that he doesn't work the title theme into the film score the way John Barry did (the title themes often come very late in the game, probably to stop them leaking). Would Newman want to do this, and if so, how? Would he write a title theme or the artist, or would the artist write it for him? That's not something that I can answer, but it is something that I think is the kind of decision that would need to be addressed if Newman were to work with EON.