Yes, but I find it very hard to belive that you don't know that this difficulty is increasing every 11 days (between 12% - 20%). Your calculations are misleading because you know very well what I'm talking about. It's not good for the image of your company to state false numbers, the difficulty it's not static. Present all the risks with buying cloud mining contracts so the costumers can make their calculations . Don't mislead costumers with false calculations, we had enought companies like this!
It's not just the difficulty that changes. The price of BTC also changes.
Sorry, $2.6 per GH/s is just not competitively priced at all. No ROI for customer at all locked in for a year, only profit for provider and that's it.
Gotta be much lower than $2 per GH to even be considered.
It's all variables and it's all risk. Whether or not you choose to accept it is the question. You can't just make a blanket statement of "if it's not under $2 per GH, it'll never ROI." If the price of BTC shoots up to $1000 tomorrow, that $2 per GH will ROI just fine.