Look at a company like BASICmining, their share value reflected their current equipment without any kind of development of their own.
You don't look at it and say "Oh this won't be profitable a year from now!". Obviously every company is going to attempt to adapt, whether it be purchasing new equipment or making their own, but so far I have noticed that current hashrate is the dominating factor of share value.
I should have added one last assumption:
"The company continues to adapt to increasing difficulty through various means".
Same with ASICminer. You don't base your annual return projection on a constant hashrate for an entire year. You expect them to continue growing, but the current hashrate is all you can base the true value on as adaptations aren't as predictable.
In the end, the current dividends are what matters to people, and from there you can only make guesses on the miners ability to maintain this. 36% is incredible.
One interesting concept we should all consider is no longer the change in hash rate itself but rather the expansion of the number of companies producing ASIC hashing devices. We currently have 3 maybe 4 players actually producing and delivering ASIC devices right now (for the past couple months). Right now the total network hash rate is exploding. I've noticed approximately 50-100 Th/s added just in the past week or so. With production ramping up at these 3-4 factories right now plus the countless new entrants into the ASIC bitcoin mining market we can start looking at increasing network hash rate as a function of the number of ASIC manufacturers.
All these guys are promising delivery in fall of 2013: FastHash, KNCminer, Bitfury, (plus some chinese ones that could be scams) (plus ActiveMining VMC of course). So the number of manufacturers is set to double in the last few months of this year. What will this do to the growth rate of the network hash rate and consequently the difficulty level?
I love this stock and I'm not selling FUD here. I just think this is a factor worth serious consideration when trying to make projections.