Then why should the increase stay at 17% (who would buy those asics)
rephrase, don't understand what you are trying to say.
These are preorders beeping shipped and added to the network hash rate. At 17% difficulty increase no one would buy asics, because they have negative ROI. Therefore the difficulty will not increase that fast. I believe its going to skyrocket until august then rise at a low rate (like 1-5% per cycle).
it's too late, we're still trying to catchup to the hardware sales, avalon has sold 500,000 chips for diy builders, adding 125theta. doesn't include bfl sales or KNC.