I am not sure that ATC does see the flight plan as a whole, generally. But it depends on which "ATC".
The 8.33 proposal is completely nuts because it is 100.000% driven by job protection in the national CAA frequency allocation offices.
I am not aware of a cheap solution. One can replace the KX155/155A radios with a KX165A but that costs US$4k plus installation (which is nil if replacing a KX155A). The Garmin x30 units are 8.33 also, and quite popular. My guess is that somebody will bring out a cheap radio with 8.33 - it doesn't cost anything to do that (it is just software) since all the stuff is synthesised anyway off one crystal.