Is it safe to go i7 7700k and the new 200 series mobo?

[pastrychef]

M.2 is a different standard. The connector is completely different from SATA. NVMe (and AHCI) SSDs are PCI-e devices. There are M.2 SATA SSDs too, but they don't offer any performance advantage over standard SATA SSDs.

Here's a more detailed and better explanation: M.2 - Wikipedia