"While system and game balance concerns make it unrealistic to allow all existing equipment to be augmented through Trial of the Magians, we intend to expand the system in such a way that players' most precious acquisitions can stay fit for active use long after the level cap has been increased." - Dev. team regarding what equipment will be available for Trial of the Magians.
While certainly just speculation, based on the above I sincerely doubt that the pool of existing items which can be augmented through Trial of the Magians will include NM drops. Perhaps I'll be proved wrong, but my guess is that if the weapon or armor doesn't come from an endgame event, it's probably out. In additional to relics and mythics, my guess is that we'll be able to augment AF2, Homam/Nashira, Abj. gear, Nyzul gear, Salvage gear, and maybe AF+1.
Maybe Square Enix will turn around and surprise me with the range of equipment available for Trials of the Magians come June, but I sincerely doubt it.