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.