I don't think it was KDE 3 -> 4 transition that killed khtml.
I was only around in the last year or two but KHTML [0] was mostly developed by a single volunteer on his spare time (Hi SadEagle in case you're reading this). There were occasional commits by other people but the majority of KHTML's development was done by him.
You see, Konqueror as a web browser didn't even have a single full time developer. That was the beginning of browser wars when Apple and Google were both funding Safari and Chrome with millions of dollars.
It was not really feasible for KHTML to compete with so many new specs being introduced to the web.
It's still fascinating what they achieved though. At the time KHTML was the first to pass ACID2 test and beat competition performance-wise in many aspects.
This is all what I can recall so don't consider it 100% accurate but I'm pretty much sure about the main point, which is that it simply was not viable to develop khtml from a practical standpoint.
[0] Quick note that Konqueror itself was created and maintained by David Faure, who maintained KDELibs (Before it became KDE Frameworks). David was a sponsored full time developer but he wasn't doing a lot of work on KHTML and KJS (The browser aspects of Konqueror)
That's fascinating, also that it was written by a single person. I remember how surprised I was when I discovered that Konqueror was at that point in time on par or better in terms of rendering quality compared to Mozilla and others. Also browser speed, memory usage etc. was just flawless. But yeah, IMHO one person projects are doomed to be abandoned unless the person is really dedicated to that project. (glibc maintainer Ulrich Drepper is probably a well-known counter-example)
I was only around in the last year or two but KHTML [0] was mostly developed by a single volunteer on his spare time (Hi SadEagle in case you're reading this). There were occasional commits by other people but the majority of KHTML's development was done by him.
You see, Konqueror as a web browser didn't even have a single full time developer. That was the beginning of browser wars when Apple and Google were both funding Safari and Chrome with millions of dollars.
It was not really feasible for KHTML to compete with so many new specs being introduced to the web.
It's still fascinating what they achieved though. At the time KHTML was the first to pass ACID2 test and beat competition performance-wise in many aspects.
This is all what I can recall so don't consider it 100% accurate but I'm pretty much sure about the main point, which is that it simply was not viable to develop khtml from a practical standpoint.
[0] Quick note that Konqueror itself was created and maintained by David Faure, who maintained KDELibs (Before it became KDE Frameworks). David was a sponsored full time developer but he wasn't doing a lot of work on KHTML and KJS (The browser aspects of Konqueror)