This will have a big impact on performance so if you are in the market for a new PC or mainboard make sure it is “NVme” M.2 compatible and not just the slower NAND. Yes these drives cost more but not significantly so as of yet.
However do not despair, if you don’t have it already there is likely to be PCIe solutions on the market and if Direct Storage supports it (and I feel it will) other possibilities may include two or more SSD’s in a RAID-0 configuration.