ASRock announced board B150M Combo-G mainboard with Socket 1151 and ram support for DDR4 2133 / DDR3 1866 (OC), up to 32G:
Of course, you cannot combine the DDR4/DDR3 rams, but the sole possibility of running Skylake with DDR3 might result in some interesting scores. Or at least interesting regults in general. Altrough not mentioned on the case, the board will support also DDR3L, as Skylake does support them too
Other that this it is not very interesting board: chipset is Intel B150, two PCIe 3.0 ×16 slots (CrossFire), one PCIe 3.0 ×1 slot. 6 x SATA3 and one SATA Express for HDD's, six USB v3, two USB v2, Giga NIC and the usual audo and video connectors.
They could be even a bit limiting, as Skylake support HW acceleration of 4k content, even the best output can do only 30fps at 3840×2160 or 24fps at 4096×2160 resolution.
So for 4k usage - get a dedicated graphic