my apologies, to clarify, I was suggesting that you 'snapshot' the net hash rate at the point of the block hash creation, not a continuously changing value. I.e. you wouldn't know what the block hash would be prior to the creation. this would obfuscate the value of the block until it was announced prior to mining.
You could just use blockhash as a rnd function seed to the same effect - this is what Doge, Lotto, and all the other pseudo-random coins do.
You cannot predict block values 2+ blocks in advance (with the current CGA or any other random reward coins that I know of), but you always know the reward while you are mining for a given block.
Using diff and height in GetBlockReward without KGW would actually make future blocks predictable as well (up until the next diff change), so I am very curious to see what s4w3d0ff produces.
I am not trying to solve this issue anymore. Block rewards will be 1/diff with a bonus block when block# % diff < 0.5, No other changes other than removing KGW.