Mining is over,
Difficulty rise 33% each 10 day, Diff coming 1.2 bilion and for next 10 days coming 1.6 bilion, and so forth,
for next 6 montth difficulty 1000 bilion, and for next 12 month diff go above 50000 bilion !
Calculation is simple, BTC mining is dead in April 2014g, game over,
You can try calculate, and see, game is over in April 2014g, no more mining profit.
http://mining.thegenesisblock.com/
your profit calculation is based on BTC but expect 10k price in 2014 and it will fit.
The BTC price in 2014 should be min. 100k usd usd that mining would be profitable, but its inpossible,
because if coininues this trend BTC price will be in the next 5 years 100000000000000000000000000000000 USD