Keeping it simple as I can.
Approx 2500 orders there will be more orders as time goes on of course but then every order number doesn't = an actual unit.
I just assumed the SC single per order = 40Ghash
So I'm gonna give it a range
50 Thash -> 120Thash 4-10X difficulty
Personally I think most GPUs will become unprofitable at the lower end of that threshold and I'm not sure how many FPGAs are out there so I'd say -80% of the current hash rate based on GPUs will dissolve. So +/- on that by 20%
As for Shipping times: BFL gave themselves till OCT +2 months and according to our records they are about two weeks slower than they say 4-6 weeks = 6-8 weeks.
I'd say the very first shipments for the first month of orders will start shipping last week of Sept until as late as the start of the new year. (Oct + 2 months plus "awe screw it it's only two more weeks late" factor)
There's roughly 2000 orders for the first month that technically need to be shipped by the end of that period. But If they get the first batch out the door close to their stated targets then would the guys further down the order list really ask for their money back at that point?
So I'm thinking
4-10X difficulty increase (+/- 20% Hash) between Oct 2012 and Feb 2013
But what happens over the following Six months should be interesting...
If you just tripled your return on your initial BFL product by being an early adopter wouldn't it make sense to buy MORE while the difficulty is low so that when things stabilize you'll have a bigger slice of the pie?
I think the graph of total hash power will look surprisingly similar to the above. Spike, small dip, flatten out with easy rise.