More likely, if it reaches $0.30 per day per ghash, it will be more like F@H. Only enthusiasts will support the network. The rest will just buy. Of course, this means less security on the network overall.
I said profit... Meaning something like $2.70 operating costs + $0.30 profit (roughly 10 %) = $3 per gigahash per day. Obviously these numbers are just very rough guesses but shouldn't be too far from the reality.
High difficulty and low security can't coexist AFAIK....
Maybe I'm using the terms wrong, English is not my native language.