eventually, the subject of the board's existence will be discussed to death
This is very true, even the forums about Chris Chan either became about other weirdos or their personal lives. Communities need to be able to evolve or have some broader topic, even /m/ has accepted discussing sci-fi/cyberpunk in general rather than just mecha anime because of how long-lived the community is and everything old has already been discussed and or hasn't been translated.
Neo-meguca gets it right - you somehow have to discover the right domain for it, get used to the controls, lurk enough not to make a fool of yourself, pass some anime-based CAPTCHA etc.
As someone who has lurked there, there was some pretty interesting cultural stuff happening there.
The board itself changes URLs and is found so often because it is designed to be linked to. It is a "streamboard" and is linked to on 4chan and r/a/dio commonly.
The anime based captcha also is easily bypassed by just clicking the character that appears multiple times.
It also essentially just a discord server that occasionally talks about 4chan meta, but the quality fluctuates depending on the year and day moreso than most board. Most of the old guard has already fucked off to discord or "bunkers" which are more obscure and often have posters intimately familiar with each-other so I don't think it's necessarily the best system.
I only wish it was federated in some way.
There is (was?) a webring when 8chan first died. The problem with federating sites like imageboards is that the administration/userbases of such sites get ornery about each-other because of the different philosophies they have.
Aside from the big boards becoming shitty they just sort of fizzled out, Probably because the teens who ran them grew up. Not a message board but http://www.baka-updates.com/
is a good example of this happening to a lot of the 2000s imageboard-wapanese crowd.
As well, the Baka-Updates team continued to grow older. An increase in responsibilities with work and new families meant that we could not commit as much time into maintaining the website. Therefore we have decided it is the right time to shut down.