You made me curious as I'd never heard of any of these editors... (except for Slickedit, I think)

A bit of digging around:

Brief seems completely dead, was killed off by Borland.

Multiedit seems operational: http://multieditsoftware.com/ It doesn't seem to active, but you can still buy the product.

Semware is still technically "alive": http://www.semware.com/ It was last updated in 2005, so there's that :)

Slickedit: is definitely operational: https://www.slickedit.com/ I have no idea why you're counting it as dead?

Epsilon: seems operational http://www.lugaru.com/ They even had a release in 2018.

To also clarify my previous statement, in the history of software, there's pre-mass PC and pre-internet. In my opinion the 2 periods are not comparable. Anything which was launched before 1995-9 or so is way more likely to have died. The mass PC and the internet have offered even commercial products much higher resilience.

Now, if a tool for developers reaches the mainstream, it super likely to stick.

I find very often that arguments by Emacs and Vim users come from a time before 1999 or so, when companies were super volatile. Look at this: https://www.joelonsoftware.com/2003/08/01/rick-chapman-is-in...

The list from Softletter in the spolsky link kind of illustrated my point. Most of the editors I listed were big sellers until 1997 or so. And most of them are effectively dead with the exception of Slickedit. The reason I switched to vim was the lack of a decent text mode editor for Windows in the early 90s. I'd likely still be using Slickedit otherwise.