Ordered 7700K yesterday and I could pick it up from local store but there are no interesting motherboards on stock so will wait till next week.
Funny is that some stores have listed motherboards which are not listed on manufacturers sites. Like MSI has no MPower and Gaming M6 motherboards listed and there supposed to be 4 models. ASUS is overpriced comparing to other brands and Gigabyte is as always releasing 20+ motherboards and I bet that as always will have problems with BIOS for couple of months.
There are maybe 5-6 motherboards with guaranteed 4000+ memory support out of maybe 90+ with Z270 chipset. So far only MSI and ASUS.
At the end there is nothing really new comparing to Z170.
Looked on the Asus website CPU support page for my Z170 Pro and Kaby is not listed yet. Maybe they just haven't updated the CPU support list because I found another website that listed that board as Kaby ready. I fired off an email to Asus support asking for confirmation.