My point was that outside of the summer blockbusters, sound editors are unlikely to get the budget to do any sort of fancy spacial processing. Mono will be the same no matter how many channels you have available. Heck, more movies had surround info encoded 25 years ago than do now.
Hmm... What kind of movies are still being mastered in mono for Blu-ray? Just curious. The only mono Blu-ray titles I seem to have in my collection are some Criterion Collection reissues of old classics from half a century ago. Pretty much everything else seems to be mastered or re-mastered in 5.1 or 7.1. My expectation is that majority of the titles that will be released in Ultra HD Blu-ray format in the next couple of years will have DTS:X or Dolby Atmos tracks. Granted, many of them will be blockbusters.