Those who have gridseed units (and didn't pay stupidly much for it) will be able to survive a much larger profitability drop before reaching a point where they have to shut down.
Except, of course, when the new ASIC farms come online in the next 3-6 months, and everyone switches away to nScrypt and other algorithms which these ASICs can't handle.
At the moment the ROI for a Gridseed is in the 9-12 month range (accounting for difficulty), and I have little faith that straight Scrypt based coins will remain profitable for that long.
I think GPU mining will remain the best long term bet for quite some time now.
My point is not about ROI about rather about running cost.
These gridseeds have a very low cost to keep running, which means they'll continue to account for a large amount of the network for scrypt coins, even while profitability continues to drop.
And yes, my point is GPUs will either shut down or switch, thus leaving ASICs as only viable scrypt miners.
While ROI is relevant for the purchase of new units, it is not for the large amount of existing units already out there.
Existing units will keep running until the profit drops below the cost of running them.
But I already addressed all of that in my earlier post.
I don't know about the low costs of running things. Right now 1Mh required 300 watts. I have heard that power is the barrier in producing these ASIC's that can mine scrypt. AMD and NVIDIA have been spending millions in R&D to get these chips to be more efficient. Heard that even at 20nanos these things still suck power. They would love to omit those power connectors and keep you from needing to upgrade your power supply. I can't see how some fly by night is going to beat AMD and NVIDIA on R&D.
The one offering I am hearing about is the Titan, its clearly stated that the miner can be pre-ordered without a Power Supply. You should ask yourself, why a $10,000 miner is lacking a powersupply. Perhaps the requirements are going to be steep. Lets say 100Mh, is cut down to 150watts per 1Mh, which blows away the big boys like AMD and NVIDIA by 100%, that still requires a 15,000 watt power supply. What these preorders don't tell you is that you may need to spend another 10 grand on the powersupply unit, and maybe even require 3 phase power to run your miner.
So far, there is not even a jpeg of one of these units, and I sure have not seen the specs of how much power one of these Titans will suck, and that is as much of a consideration as the 10K pre-order price.