Does anyone know how these will do in memory hard algos like Kawpow?
There are not even synthetic tests yet, and you are asking for mining tests. After the video card is released, miner developers will need time to optimize their miners for the new video cards.
And Kawpow works very well on cheaper video cards.
No matter how well behave these cards right now mining is not profitable at all,the prices of such latest series cards will be expensive and not at all worth for mining unless someone will take the risk of building a rig with those hoping for a bright future in mining and he will have predicted x3-x5 prices of such cards when that happens.
That though is extremely unlikely and the fact that most people are not caring at all about the Nvidia latest series and AMD latest series available chances will be high that the same dis interest will be also on the upcoming top series.