It's just an arithmetic logic unit for tensors. It's not at all like a crypto miner that implements a single algorithm.
They shipped Deep Learning Accelerating Card SC1 at $589. You can't buy it right now because it is sold out.
But right now they have what they need.
BTW, I would be curious on the TPU 3 design considerations to better support dynamic routing with Capsule networks. I suspect creates different memory access patterns and where the big power savings are at today.