Well, that's a textbook example of a straw man argument. I mean, come on. What's the point of this stupid inflammatory BS? The post you quoted said "there'll always be a niche who want 5+ m.2s". How is
more than five the same as "a couple"? Come on. Either read more carefully or stop trolling. Also, where have I (ever?) mentioned mining motherboards, let alone called them "mainstream"? Or are you just completely making stuff up at this point? Please, go back and re-read that post, then we can talk.
For servers. Servers are the main driver behind development of new RAM and PCIe standards. They want (and need) all the bandwidth they can get their hands on.
The preliminary specification for PCIe 5.0 was published in 2017, and it was finalized in May 2019. Work on the 6.0 specification was announced a few weeks after the 5.0 spec was finalized, and is expected to be finalized this year (though it's not unlikely that it's been delayed due to COVID). If anything, the aberration here is that 3.0 lasted us nearly a decade - that's just quite weird, all things considered. 4.0 was late; 5.0 was worked on to ensure it wouldn't be, same with 6.0. When 6.0 is finalized, no doubt work will start on 7.0, though there's a point of diminishing returns fast approaching in terms of signal integrity and possible trace lengths, so we might see some alternative technology take over by then.