Don't forget that 22nm and below uses double patterning. That means 2x as many masks, and fabrication takes 2x as long using the expensive fab equipment 2x as long.
So people don't take my words out of context. I never said KNC was giving their employees busy work or that we won't eventually see a sub 28nm processor. It is just that I strongly (and am willing to eat crow if proven wrong) do not believe the economics make sense for sub 28nm in 2014. Someday but not in 2014 and probably not in 2015 either (although I am less certain on this).
Some people pointed out that well ASICS have high margins. Yes they do but the margins are collapsing rapidly. We have gone from $50 per GH to $10 per GH with Cointerra offer <$3 per GH in Jan, and some lesser names (questionable) offering sub $2 in Feb. I have no doubt raw chips will see $1 per GH in 2014 and prices will only go lower. If your cost per mm2 is double that of 28nm the fact that your chip is smaller isn't going to do much good to the bottom line. It doesn't really makes sense to spend $4M to $8M extra cost to have chips with a HIGHER marginal cost than both your own chips and your competitors. Eventually 22nm and below WILL be cheaper per mm2 than 28nm but that won't happen for a while.
Some people have also pointed out that 22nm uses less power and at nominal clock that is correct however it is pretty easy to make silicon use whatever power you need. Drop the clockrate 20% and you can probably drop the operating voltage 10% to 15%. The exact amount will depend on the chip design but I am sure all the companies are looking at how low they can undervolt their chips. Either ship future boards with an adjustable voltage regulator or swap out one resistor and have it operate at a new fixed lower voltage. Power in is silicon chip is reduced by the square of the voltage reduction so TADA like magic a 10% to 15% drop in voltage means 20% to 30% higher J/GH. 22nm in theory (and reality always falls short or GPU wouldn't need to get bigger and more power hungry) is 30% lower power.
So 30% lower power with $5M in NRE + 2x (maybe 3x) higher marginal cost or 30% lower power by replacing a $0.10 resistor. Hmm that is a tough one? Granted the resistor option means your chips are slower but as pointed out to justify a lower process node the marginal cost is very low. So take a Sierra as an example (the same thing would apply for a Jupiter or Cointerra rig). Drop clockrate 20%, voltage 15%, and your use 4 boards instead of 3. Now you have a marginally faster unit (1.3 TH/s vs 1.2 TH/s) which uses roughly the same power, with same chassis, same power supply, and same boards.
In time the premium on 22nm over 28nm will drop lower and lower and eventually will reach parity with 28nm. Just like 28nm eventually reached cost parity with 40nm and 40nm reached cost parity with 55nm. Around that time a respin with an improved design, enhanced functionality, and the benefits of lower power consumption and margin cost makes sense.
Don't believe me how about NVidia. NVidia estimate for cost parity between 28nm and 22nm is Q1-2015 and cost parity between 22nm and 14n is Q1-2017. NVidia and AMD won't be using sub 28nm on GPU in 2014. I mean just think about that for a second if you think 16nm SHA-2 processors are right around the corner. Two of the biggest companies in processors will be delaying even 22nm until 2015.