Damn, to the Astros? That wouldn't even be fair. I would have thought another starting pitcher and/or some pen help would have been their move.
I like the idea of Realmuto, but I just see two issues with it
1. Not giving up some key prospects. Guys like Fedde, Robles, and Soto are pretty key right now. Either we expect them to play a major role in the near future (Fedde and Robles), or they are much more ceiling than actual value (Soto in particular, but Fedde and Robles have elements as well). We'd have to give up Soto and some other pieces to even get them to answer the phone. Which is fine, but leads us to ....
2. Matt Wieters' contract. Look, he's a BOras guy. The Lerners are in with Boras. So I highly doubt they're going to let Rizzo trade for Realmuto and give him Wieters' playing time in Wieters' contract year. Boras would become a HUGE PIA, and pretty much force the Nats trade Wieters. And it'll be an issue until it happens. (And also, I'm kind of hoping that Wieters has a huge bounceback in his contract year).
Given that the Marlins are asking a king's ransom, it's clear they are in no rush to trade him. I would hold out until next offseason. This gives the Nats more leverage and ammo for trading. It determines if MAT is a flash in the pants, or can actually produce at last season's levels. The Bryce Harper situation will sort itself. Wieters' contract will be done and we will have had a really good look at Severino. And Fedde and Soto will have continued to progress, thus making themselves more valuable.
Rizzo will probably determine the asking price right now, just in case Wieters is a total failure or gets injured. But honestly, I just can't see that deal happening right now without at least moving Wieters somewhere. Maybe the Marlins take him?