100 times difficulty ~ 100,000,000 GH/s ~ 1,000,000,000 USD investments in mining gear
Who's gonna pay that?
You assumed prices of $10 per Ghash/s. It is well-known current ASIC vendors have insane margins on the raw silicon. As a matter of fact, Cointerra is already selling pre-orders $3 per Ghash/s. Watch the price drop to $1 or less per Ghash/s over the next 12 months. Therefore a $100 million investment in mining hardware is all you need for the network to grow to 100 Phash/s. This will happen by September 2014. Watch.
Well, imho, all vaporware of new companies could be getting very slowly to the market. Every new company with a new ASIC will get setbacks to mass produce fully functional hardware. Technical and organisational.
Even the succes stories ain't spotless: ASICminer doesn't show their projected 200 TH which, iirc, they would have deployed at the start of last summer. Bitfury ASIC retail miners had to rerun parts of their production. 100th mine has been several months delayed and then you also have the usual suspects BFL and Avalon. Completely normal in every starting business and to be expected also of all other newcoming companies, and BFL again for sure, claiming to not need a prototype for their 28nm, since their models are now superior.
The incentive to invest in and to distribute retail products is also dwindling, since one has to compete with mines like Ghash.io, which runs the most efficient chips atm against manufacturers cost, which could be under $1 per Ghash/s according to your assumption. But they probably won't compete with themselves, just building and maintaining their share of the network. So they will follow retail and competitors, not lead them, but they are king for now.
Retail will slow down its pace first (happening right now), due to inherent high cost structure and lower than expected returns of their capital already fixed in miners and preorders. Generated income will probably hardly be reinvested after being scared in these first ASIC production rounds and by current jumps in difficulty. And daily amounts per individual miner are relatively small and they have to save many days to buy a (then hopefully cheaper) miner. Slowing the growth pace more and more, since they earn less and less and are mostly still in the red for their earlier investments.
Public companies like ASICminer come next, due to 'dividend losses' and losing the energy race accelerated by a shrinking share of the pie. Unless they (have) invest(ed) sanely (when they ruled the network) and some monkey comes out of their sleeve on one of these days. AM still makes a lot of investment capital every day, but hardware production and growth of mining capacity is slow compared to demand up till now.
Large private mines will rule anyway and the forementioned Ghash.io is the only serious one right now and they soak up around 20% of the daily production out of the market which is hardly needed for their expansion (they mine per day a private gross investment capital to add ~100 TH mining capacity) and which is not available for other parties to reinvest.
Even if the cash to invest is available (current pre-orders don't run as fast anymore it seems, look for example at HashFast 1st batch Babyjets), the production capacity could very well being the factor restricting a continued high growth pace.
I can't predict the future however and only expect a bumpy road to this hundredfold. Price drops can slow down growth also significantly and the other way around. But I do hope for a 100 Phash/s network rather sooner than later, since it is a positive sign for bitcoin. But not so much for this mine.