As to who will pay, there is a sort of hint in CAA stuff that the introduction of UAV's and their need to "sense and avoid" with at least as good collision avoidance as humans in VFR, may result in some money from the UAV purveyors.
Personally, I will believe it only when I see it.
And none of that addresses the fact that many gliders and light a/c can't fit a power-hungry thing for weight, power or space reasons - ICAO still have not approved a lower powered option, much as the CAA say they are pursuing it, and even if they do the battery and unit still have to get into tight cockpits.
Chris N.