Hm, thinking about the general issue, I always wondered...
Wouldn't there be a method to implement it at least in some locations or under specific circumstances?
Ever since CQC (now Arena) hit, it being a simulator not tied to any in-game mechanics, I could imagine specific Maps there where such Newtonian elements could be tested (benchmarked if you wish) and to provide an additional challenge.
If successful/appreciated, later it should be possible to implement it at least in "special locations" - be it "Ionic Gas clouds within a System interfering with and disabling some Computer Assistance" or proximity to specifc (not yet in Game) SciFi Objects or Planets/Phenomenon.
Placing some form of Conflict Zones or other Combat Opportunities there specifically would do the trick.
You can be sure that even me that doesn't like having it as a Universal Flight Model, I'd certainly check out these locations to see how it affects combat
So overall, I believe the current Flight Model does not have to remain exclusive. Frontier could come up with various means to selectively implement specific "Newtonain locations", either in CQC or the ELITE Universe without any lore breaking.
Wouldn't be a bad idea and if nothing else - offer some interesting twist to Combat in these locations.
For old times' sake...
How about one day we get pulled out of Hyperspace by Thargoids/something else and end up suddenly having to deal with Newtonian Flight Model?
There you have your "special location" and it even fits existing lore 100%
The suggestion is not bad, but in my opinion there are other areas which need work before they should put time an effort into it.