Why future-proof your board when your CPU will limit you sooner?
I think there's no point obsessing over your motherboard's longevity besides making sure it has strong VRMs, features you'll realistically need today or within the next year, and enough room for one drop-in upgrade. Beyond that point, you're just paying for theoretical value that you may never even benefit from. That's especially true for gaming PCs, where the CPU and GPU usually determine when your build starts feeling outdated, not the motherboard itself. Sure, if you're an early adopter, splurge on a high-end board by all means if you're willing to stick with the platform, but for everyone