But like Stuka87 showed with his link, nothing has really changed since then in that regard. As long as a person is using a PCIe 3.0 slot (and at 8x and above), there's really no difference. In fact, I ran my GTX 1080ti at 8x for around 6 months while doing Folding@Home, and there was literally an insignificant difference.
The demand on PCI lanes comes from the bandwidth the GPU needs to communicate with the CPU/Memory, that's basically proportional to the speed the GPU and fill and uses it's memory, so as video cards get faster they'll have a greater overhead on PCIe although right now it looks like the impact of bottlenecking PCIe is very small. You can run most high end video cards in 8x mode and get basically the same frame rates.
Really these features need to come from the motherboard, get a motherboard that can allocate lanes of PCIe through the BIOS, that means limiting the x16 slots to x8 and then freeing up alternative PCI x8 or x16 slots
Main thing at the moment is that NVMe drives are not great upgrades for gamers, the additional data rate is only helpful in a very small number of circumstances. Almost no games load faster because of NVMe over SATA, I have 2x 960 Pro's in RAID 0. The biggest benefit I've seen so far is smoothness in loading in game assets in open world games, most notably Subnautica where a lot of people suffer extreme lag as the engine streams in new biomes as you traverse the map.
I do know as games start to move towards 4k appropriate textures and huge open world we're starting to look at games in the 100Gb+ size range and even larger in future, faster drives, faster PCIe and more memory is going to be important. Many games today still use absolutely hideously small textures, the ones from the 4k pack for R6 Siege are a good example of textures done right, but the install for the game is 116Gb for me. I'd love to see similar levels of detail for other modern AAA games, especially some of the open world ones.