For a Mode S box like the Trig, all you need for ADS-B is a super fancy certified GPS box that costs a whole bunch more than the Trig.
The set up of ADS-B include things like wingspan and antenna location so aircraft on parallel taxiways won't cross wingtips.
Is that level of certification needed for GA away from major airport taxiways? Your off the shelf GPS will do quite nicely in the air and give the big guys sufficient warning to stay well clear of you. Will IAOPA get the ear of the regulators on this one -- stay tuned. More likely the electronics people will develop an ADS-B box at a GA affordable price before the regulators come around.
The PowerFlarm gives very good information on ADS-B; so, you do have timely information to get out of their way.