12 or 10nm chips of any sort will not be available from anyone for several more years, on top of that, so far looks like <12nm is going to be reserved for high complexity chips and not simple boutique ones like mining ASIC's.
Why? Because of pricing?
That would be one way to look at it. The complexity and circuit density of the process so far is dictating that the dies will be fairly large/high value. IMO probably because they can fit so much into the dies that the cost to connect simple circuits to the outside world makes them a moot point. ref the threads here a while ago about IBM announcing a 7nm test chip