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).
Difficulty just increased by 10% and the next increase is predicted to be similar.
Doubling time to get to 1 EH/s from here:
10% diff increase every 14 days = about 100 days
7% = about 140 days
5% = about 200 days
Yeah, I think it´s highly likely that you´ll hear the term exahash in the coming months and it seems a given that total hash will be there in - say six months? Any shipping backlogs at Bitmain?