decrease in hash rate and this big is mainly due to paycoin and as long Gaw keeps the promised price of around 20 usd it will continue.For sure some miners are switched off and many big farmers are selling , check bitmain site selling the s4 by the Phs.
I also have seen big sales (dont know if true) 100 sp30 100 teraminers and sure the new prices from sp tec help much.
Generally there is a no Roi period since the price of BTC is low and this is a reason for all.
if we see an increase of the price to 400-500 range then will start again fast.
Since many companies now accepting bitcoin and the same time sell it for fiat the price
is unlikely that will go up soon
In case you didn't notice, SHA Paycoin mining was only for a limited time. It ended today at noon EST. So no, this trend will not continue. Everyone's back to mining BTC and the network will continue to grow... hopefully slowly.