Intel's Coffee Lake 6c/12t will require a new Z370 board but will support Thunderbolt 3

So it seems that Intel is using the same LGAA 1151 socket that they had in Skylake and Kaby Lake.

Previously, even Z170 boards got Kaby Lake support (albeit I think they had some features missing).

Intel has dropped Z270 support for Coffee Lake (confirmed via ASRock's twitter, which they later deleted). The Z270 is only about 7 months old.

Here's more info:

https://www.extremetech.com/computing/253580-asrock-confirms-intels-coffee-lake-cpus-will-require-new-motherboard-socket