When you go to 20nm process technology?
TSMC is taking orders at affordable prices since 2014.
I expect you'll get the answer to this question then Bitmain announces a new generation of ASIC, not just a repackaging like the S4+.
You might find that Bitmain has a different view of what constitutes "affordable" than you do.
1) Development of topology ASIC
2) Production of masks for photolithography
3) Protection of intellectual property
For the entire set - 160-200k ..
You can haggle ( looking where to place an order ) .
I think for BITMAIN this problem is solved.