With the current regs here in the US I'll go out on a limb and say not for another five years. Unless people are willing to mount multiple antennas and receivers in the wing tips and fore and aft it won't be reliable enough to sell. From a marketing standpoint I bet the manufacturers feel that is a big hurdle to overcome.

Some people will go ahead and use the current system on glow planes and claim that it is perfectly fine and what's the big deal. For the folks in this forum to do the same will only speed up the regulating and possible demise at some venues for your chosen aircraft.