I made a thread to help people predict this. Said 6 to 8 PH/s by end of the year. Honestly I think now it will be closer to 8 to 10 PH/s. By mid 2014 we probably are looking at 15 PH/s+ if ASIC companies serious cut prices (say <$2 per GH/s delivery in 30 days or less) we could see more than 20 PH/s. I don't think 30-40 PH/s by end of 2014 is that conservative. Worst case scenario we way overshoot and end up 50-80 PH/s and new sales flatline for a while.
I hear it will be around 30PH by the end of February by some large players in the mining game. Personally I think it will only be around 15PH by then but then again we'll see.