I used to believe quite a bit in future-proofing but not so much anymore. A Mac is a system and there are many possible bottlenecks/pacing factors besides RAM. Even if 16GB of RAM may be enough 5 years down the road, there are still graphics, processor, hardware encoder, I/O etc. to think about.
I’m using an Oct 2008 MacBook. It’s only usable because I could upgrade the ram. It’s the upgrade that kept the machine viable for a variety of uses. Although 8 now probably has more shelf life than 2 did then.