Seems unlikely. TDA is good but I can't imagine some team being willing to part with a starting caliber LFer for him.
The fact that a move for Realmuto is so "out there" that no one would really have thought about it does make it feel like an AA type of move since no one would see it coming, but it just also feels like a desperate play from J. T.'s reps.
Since it has everyone abuzz though, I wonder if we're not all looking at it from the wrong angle - and that the play he'd make with d'Arnaud would be part of a much bigger trade. This one's a whopper, but probably not a whole lot more of one than signing Realmuto in the first place, so...
1.) Sign Realmuto to hit behind Freeman, then
2.) Ship d'Arnaud, Riley, and Contreras to Seattle for Seager, Haniger, and $10 million.
That would mean you get Seager for free (more or less) this season. If the money's there to add $25 million AAV of offense, adding Realmuto at $23 million and Haniger at $3 million is awfully close. Gives you the other LH bat you're looking for and keeps two RH bats sandwiched around Freeman without costing any of the pitching depth while keeping the better defensive catching prospect to eventually split time with Realmuto...
Acuna, Freeman, Realmuto, Seager, Haniger, Ozzie, Dansby, Ender/Pache
Seattle could then take the money they saved to sign someone from the Pederson/Mazara/Duvall group to keep RF warm this season while they wait for Kelenic - if he comes up this season (or if they want to give one of those guys a multi-year deal to guarantee they get them) whoever they sign would shift to their DH spot.