I'm being a little coy because I do have a very detailed proposal.
In want the JS toolchain to stay written in JS but I want to unify the design and architecture of all those tools you mentioned so that they can all use a common syntax tree format and so can share data, e.g. between the linter and the formatter or the bundler and the type checker.
Hasn't that already been tried (10+ years ago) with projects like https://github.com/jquery/esprima ? Which have since seen usage dramatically reduced for performance reasons.
You can rip fast builds from my cold, dead hands. I’m not looking back to JS-only tooling, and I was there since the gulp days.
Yeah it's a shame that few people realize running 3 (or more) different programs that have separate parsing and AST is the bigger problem.