LOL - I put in some numbers and every single miner currently available for sale and pre-order will never make ROI even with free electricity except for Cointerra IV miner - but that's assuming it is delivered on time.
I used 30% increment on difficulty. Now it may not go up 30% every increment, but the last 2 have been over 30% and it's irrelevant if the last few cycles are near 30% if your devices is already down to mining satoshis.
I'm going to sit on my sit on the sidelines with my 300GH and wait for the dust to settle. My 2011 GPU farm has already made more than coins than any ASIC could provide (short of shelling out 7 digits).