While AMD's current desktop processors already support PCI Express 4.0, Intel fans will have to wait a bit longer to get this feature. Some leaked slides that detail the Intel NUC roadmap reveal the 10nm+ Tiger Lake processors will be the first to get PCI Express 4.0 support.
Next year Intel will ship its "Ghost Canyon" NUC and the year thereafter you can expect "Phantom Canyon". The former will feature the Core i9-9980HK processor in combination with optional discrete graphics from NVIDIA (GeForce GTX 1660 Ti or RTX 2060). Phantom Canyon will feature a 28W Tiger Lake-U processor, this model will also support discrete graphics and will have an integrated 500W PSU, PCI Express 4.0, 802.11ax WiFi, 2.5G LAN, Bluetooth 5.0, USB 3.1 Gen 3, Thunderbolt 3, and HDMI 2.1. The device will also have integrated RGB LED lighting.
TechPowerUp adds that the news also indicates Intel will increase the bandwidth of its chipset bus:
In related news, we see subtle hints that Intel will give its chipset bus a major update in future generations of its desktop and mobile platforms. Apparently, future platforms could feature DMI spread over 8 lanes as opposed to 4 on current platforms, besides the update to PCIe gen 4. This quadrupling in bandwidth compared to DMI 3.0 (PCIe 3.0 x4) is necessitated by the growth in bandwidth-hungry devices such as NVMe SSDs, external Thunderbolt 3 graphics cards, USB 3.2 flash drives, etc.