"A few years down the line" is the whole point when talking about viability 5+ years down the line. My i5-3470 was good enough for me for ~10 years thanks to having PCIe 3.0, USB3, SATA3, etc. and two extra cores that I didn't need back when it was new.
Five years down the line, 4.0x4 NVMe will be low-budget stuff just like how 3.0x4 used to be a luxury but can now often be had cheaper than the nearest equivalent SATA.
Do I need 4.0 on my i5-11400 today? No. Will I toss a 1-2TB 4.0x4 NVMe SSD in it during its useful life when the premium over 3.0x4 becomes slim to none 2-3 years from now? Practically guaranteed. Will my PC be outdated compared to the latest and greatest? Sure. But I don't give a F about that as long as it still does everything I expect well enough for me and based on my i5-3470, I expect that to be 5-8 years.