By the end of the year difficulty will be 500-900 Billion. Put that in the BTC calculator for profit return. A 30TH unit will make $10 profit a day.
You know better than that. Calculators are not meant to be used for more than 2-3 months in the future. Then you could use the same calculator for the end of next year, and find out that you will need half world electricity to power the trillions bitcoin miners, the surface covered by miners will be 10% of worlds surface, and people mining will pay $100 in electricity for ever $0.01 in BTC they can mine.