I'd be astonished if they use FPGAs in production kit. Once they get the circuit design right, even a modest quantity of (static) ASICs would be cheaper than FPGAs, and probably faster.

That said, if this really takes off, I'm sure some enterprising spirit will write some software to re-purpose these things as-is (I'm thinking something like a VMWare driver to turn them into NVRAM-SANs for disposable "worker" VMs)