Eventually if it gets wider spread adoption and use then profit will self sustain at a certain point as there will be 100's of thousands of transactions instead of the few each block there are now.
That is where the steady money will come from. Until that point it is an arms race to get the most they can now.
More of these companies need to start focus on the economy of the whole things and get people spending bitcoin that way there will always be a need for miners.
Could be .
Plus with more big farms coming on line it will put it out of reach for most people.
We won't see many of them until the manufactures are done mining with them and ship all the preorders.
Sad but true.
If there is not a flood of 1TH/s 20nm miners soon, a 200A residential service will not be able to handle mining for a profit well before the end of the year.
Well I am predicting that difficulty is going to be forced to level out because miners won't have anyplace to run their miners.
I calculate that profit will be out of reach for even the big farms by the end of 2015