It's true, my last 2 payouts are exactly the same value and that is exactly because ETH values increased. But considering in the last 2-3 months the value decreased I think we will see more than once a similar situation in the next 2 years. In theory you are 100% correct, but with the growth in the market we are seeing I do not think it will happen.... Anyway we will make money from mining so we are just trying to figure out how much XD