The Dynon (and presumably Trig since that's what it's based on) transponders already meet the V2 requirements now. As does the Garmin GTX3000ES and GTX23 with SW Version 7.01 on, the King KT74 and I would guess a bunch of others.
The main difference appears to be which ones have been designed to comply with DO-260B, and that seems to be most of them.