It appears that Intel's 600 series chipset — built for Alder Lake — will not support the Gen 5.0 standard, per a report from HardwareTimes. According to a PCI-SIG certification, Intel's future Alder Lake-supported chipsets will max out at Gen 4.0 speeds running in an x4 configuration, meaning the only Gen 5.0 support Alder Lake will see is through the CPU lanes alone.
We don't know why Intel cut Gen 5.0 support from the 600 series chipsets, whether the it's cost issues or capability issues. Either way, this could be a positive strategy for Intel to keep Alder Lake motherboard prices at a minimum.
When Gen 4.0 first came out, we saw a large jump in motherboard prices due to the motherboards requiring much higher quality materials and far more PCB layers. These are both required to ensure Gen 4.0 speeds are stable. This is especially true of AMD's X570 platform which has full Gen 4.0 support on both the CPU lanes and chipset lanes. We can only imagine the same thing will happen with Gen 5.0, and probably be worse, since Gen 5.0 is significantly faster than Gen 4.0.
But with Intel supporting Gen 5.0 only on the CPU, motherboard prices may not be as expensive as they could be. It's much easier for motherboard manufacturers to build boards around one or two Gen 5.0 PCIe slots than to build the entire board to support Gen 5.0.
Plus, most consumers and prosumers are rarely saturating Gen 4.0 speeds right now, even on Gen 4.0 NVMe SSDs, and we don't expect this to change over the next few years. So this Gen 5.0 issue shouldn't be a problem for most buying into the Alder Lake platform next year.