Later in their careers, the Yonin Shu managed to stay somewhat relevant in various ways. As mentioned before, Michi turned to disco and became Mitchie and Haruo Minami deviated to rap and house music. Hachi became a target for monomane artistes, especially Akira Shimizu (清水アキラ) who'd tape up his face to replicate the veteran's dimples and wrinkles. As for Muchi, he became a meme (just in case, it's pronounced as "meem"). There are two definitions to the word "meme" I found on the Merriam-Webster dictionary, but I believe the first one fits this situation best: "An idea, behaviour, style, or usage that spreads from person to person within a culture."
From what I gathered from his J-Wiki article, Hideo Murata's (村田英雄) idiosyncratic antics became the talk of the town beginning in the early 80's via one of Beat Takeshi's (ビートたけし) variety shows. And it seems like the most popular phrase in relation to Muchi that was coined by Takeshi was "Ore ga Murata da!"/"Murata da!" (I'm Murata!), which had Shimizu and eventually youngsters mimicking this proud proclamation. I'm not sure if Muchi himself actually said that in real life - I don't really think so... - but it definitely matches his gruff image down to a pat.
Murata did seem to enjoy the resurgence in popularity and capitalized on this, as I quote, "Muchi Boom", by starring in Murata brand (of course) fax machine commercials, as you can see at the start, and even churned out a song that featured this iconic sentence. Released in 1989, the song was aptly titled "Ore ga Murata da" and is pretty much everything you'd expect of a Muchi tune. Its score is manly and jaunty and almost festive-sounding, which sort of reminds me of "Mina no Shu" (皆の衆), and the lyrics talk about the singer himself and how he transformed into the icon he was - there can only be one Muchi, none before him, none after. The one responsible for composing "Ore ga Murata da" was 奈和成悟 (I don't know how to pronounce his name) and writing the words was 田中祭鬼... I'll just call him Mr Tanaka because I also don't know how to pronounce his first name.
To end things off, here's Shimizu's Murata shtick. Admittedly, his impressions aren't as spot on as some of Korokke's, especially in his later days, but the addition of offensive humour in most of his acts is hilarious.