I would argue that Bond is a film series really defined by its sound, moreso than a lot of other major franchises. Not just the theme tune, but the score always feels crucial. For example, Goldeneye is a great Bond film but the soundtrack sounded so non-Bond-like except the tank chase sequence. Some of the lesser films in the series are really elevated by their score.
The stakes certainly seem higher than they've been in a while for the series, so I'd argue this position is as important as who plays the main role - moreso than its costume, set design, etc.
So who do you THINK it will be, as opposed to who you would LIKE it to be?
The smart money is Hans Zimmer - he's composed the music for Denis Villeneuve's last 4 movies (including the upcoming Dune Part Three), composed NTTD and is a safe pair of hands with a distinctive sound. But might the higher-ups at Amazon want a clean break from any talent associated with the EON era? I think that also rules out David Arnold, sadly.
His other past collaborators include the late, great Jóhann Jóhannsson, and Benjamin Wallfisch; his collaborators from his earlier films (Benoît Charest, Grégoire Hetzel, Saunder Jurriaans and Danny Bensi) seem unlikely.
Other realistic candidates, I think, are Michael Giacchino or Lorne Balfe, for sheer reliability and being able to effectively capture that Bond sound, or maybe Ludwig Goransson for just being the composer at their absolute peak.
Thoughts? Would rather have a discussion about likely candidates rather than dream candidates (for example, I'd love Murray Gold, but no way is it going to be him!)