The problem is keeping pace with the upstream: it's not that it's impossible but that it's very expensive — when Google forked WebKit they dedicated a large and very talented (i.e. expensive) engineering team to the project. The same could be done again but you're looking at companies like Microsoft, not startups.
Re:The Era of the Trident Engine
by MaxBarraclough on Sunday January 26, 2020 @08:16AM
(#22151924)
The resources needed to maintain a Gecko-based or Blink-based browser will depend on the amount of customisation. Vivaldi/Opera/Brave are doing fine, but they make relatively shallow changes over Chromium.
I just discovered Goanna on Wikipedia, a fork of the Gecko engine, presumably with relatively thin resources. Don't know how well it compares to mainstream engines though. [0]
I suppose the short version is that the workload is a function of the goals.
That’s the point: if you’re not customizing Blink, you’re not changing the huge influence which Google has over de facto web standards. If you want to make more than simple customizations you need a significant commitment just to keep pace with the upstream – Microsoft can afford that, Samsung can, etc. but it’s not clear that Brave or Opera can.
Mozilla themselves have been doing this with Firefox. They've been replacing C++ by Rust (with the Servo rendering-engine project). They've replaced the JavaScript JIT more than once, if I recall correctly.
We've already seen WebKit give rise to two divergent major browsers: Chrome and Safari.