What are you using to provide the 16 m2 sockets in that theoretical system? Now I can't say I've seen a consumer board with u2 but I think it'd be easier to find 1 of those than 16 m2.
If you don't have a U.2 connector, you can use a PCIe adapter card.
If you want 16x M.2 slots, you can use two 8x M.2 PCIe carrier cards.