Total hash is presently over 500 petahash so in the next months you will hear the term exahash (EH/s).
You have failed to take into account an important factor. As the diff rises and BTC/USD doesn't increase significantly or goes down older miners will be forced offline, I doubt we will see exahash in the next 6months-1year unless ofcourse BTC/USD doubles in price (Quadrople @ Halving).