Killer007

It's a picture taken at Intel Partner Seminar presentation so despite the author of the picture is unknown, the primary source should be Intel itself. You're kind of right, it is confusing. However it somehow coresponds to what we know - only higher-end processors will be launched in the late summer (the K ones) - with, so far it seems, Z370 chipset which might be just a rebranded Z270 for purpose of Coffee Lake - with other models coming out with real 300 chipset in Q1 2018. - reason to edit: text formatting

Where is Aug/September coming from? Here.

So if Coffee Lake release date is august-september and Z370 chipset launches in Q1 2018, the processors will be in stores with no compatibility whatsoever? That doesn't seem right to me.

It's very likely to keep the same 1151 socket. Maybe up to mobo manufacturers to give us support by releasing new BIOS or not.