Hi Dance

There is a point that you aren't take into consideration, you could sell your hash at any moment, so even with GHS prices falling if they take more than 254 days to reach 0 you will have that sell as an earning.

Depending of difficulty increase, BTC prices and so on you could made profit.

Agree with you that is too risky with S4 at current prices but isn't impossible

Actually I've had put some buy orders that trigger with half prices and already traded some S3 hash with very good profit