[Sanddancer]

Altera at the very least has FPGAs you can buy right now that offers DDR4 interfaces [1]. Also, I imagine a lot of this is directed towards OEMs who can get the early silicon samples of Haswell-E chips so they can start testing with them.

http://www.digikey.com/product-detail/en/10AX066H4F34I4SGES/...