I've heard lots of you asking what does profitability look like for mining Ether and the first thing that comes to my mind is that it depends! Really it depends on the price of Ether, as well as the ratio of your hashing power to the total hashing power of the network. Not to mention, e- costs.
Now we could go into a whole bunch of mathyness but lets just skip to the pretty pictures and explain them later:
Now lets look at how much $ you'll be able to make at this game:
Now using this graph, we can get an idea of what value of Ether is required to support a given hash rate. Personally, if My R9 280x card, which is burning $15/month in e-, if it's making me $20/month in profits, I'm ok with that. This means it'll also pay for itself in less than a year. Thus, a 1TH/sec, I'll still be mining if Ether is work $1. And, if Ether is worth three times as much, I'll be able to mine until the network hash rate reaches 3GH/s.
I would roughly expect the hash rate to reflect 1 TH/s per $1 of Ether. So since Ethercoin is currently trading around $3, I would expect that at the Frontier launch we might get as high as 3TH/s mining on the Ethereum network. Network hash rates that exceed the 1 TH/s value of Ether indicate that the community believes Ether will be worth more in the future than it is now, and wold be a bullish indicator.