He has a good calculation and I as certainly many others would also like to see comments on it. Comments up to this point have focused on the genesisblock calculator. This calculation includes steps and a tapering growth rate.
Didnt KnC expect to ship 500TH in the first batch (supposedly september) ? If so, there is no way the next difficulty jump (after todays) would only be to 199,126,888. Even if everyone else stopped shipping, the network hashrate would be the current 1200 TH + KnC's 500TH which gives a D of ~240M instead of 200M. And I doubt BFL, Bitfury and others will stop shipping, in reality it will be above that, even after taking latency in to account.
Of course I dont expect every KnC customer to receive and deploy their miner next week either, but that only makes it worse for those not getting their KnC gear in time.
Another thought is that the decreasing growth may not be incorrect over time, but in the coming months, I would expect the exact opposite. As KnC/Cointerra/Bitmine/whatever all receive their new chips over the course of ~2 months, I would expect to see a dramatic acceleration of the network growth compared to today. Perhaps early next year that will reverse, and the rate of growth may decrease (in %/day), but surely not in the coming months which are crucial for the ROI of most current asic preorders.