Some recent insight re: 10nm and lower nodes. Pay attention to the parts about the cost and number of masks/steps needed when using non-EUV light sources.
Current node size points and costs
*can* 7nm be done without EUV? A very cautious 'yes' if cost and production rates are no object but it will NOT be happening in this year before Q4. Otherwise 2019 is still a very safe guesstimate before any production-ready processes are starting up assuming the remaining hurdles to the EUV sources can be solved.
The 7c looks like a good middle of road target for 2019. 5 EUV masks.
That may be why GMO is saying 1st test 7nm Miner in 2018 presumably before EUV introduction. Then full-scale production is moved over to 7c when production begins. Idk, there could be other reasons.
If GMO does meet their targets for this year then I doubt the just make one or two miners. Do you think prototype is code for we are building a large scale mining facility?