I'd like to keep this one on Scrypt; the prices on scrypt have fallen considerably, but I believe they will continue to fall faster than the machines will earn until the retail price of the machines reaches production costs plus a thin margin.  I expect this to happen in the October time frame for scrypt as it's beginning to happen now for sha256.

Power efficiency is going to be a key factor. 

Looking at GAW their hosting prices are cheaper than the cheapest electricity rates in the world....makes me wonder how they do that? Ponzi perhaps?