Probably a VEGA Variant of the Radeon Pro Duo.
Or some Vega X2 part.
Miss my 4870x2. With ryzen in good shape if Vega is another hit then I may have to move back to my amd/ati roots.
My 4770k and 970 are beginning to age.
Edit: also its nice to see some development coverage for Linux BEFORE the hardware is released.
AMD could probably drop a air cooled vega for that matter, let alone a water cooled one.
A dual vega card is pretty much a no brainer as AMD has put out dual gpus of every flagship they have made since 3870x2
There was no official 390x2, only the power colour devil card. But that is really splitting hairs as there was a 295x2.
Quad crossfire.. I'm on board, as long as I can plumb it into a custom loop, no interest in an AIO water cooler.
Here's me thinking my 3770k and 670 are holding strong still. 
I don't really play any taxing games by modern standards though to be fair. Mostly Skyrim with mods, Planetary Annihilation and Rocket League.
390x wasn't a flagship at the time, the Fury X was.
Oh look pro duo.