I don't think we will ever be able to get away from bundlers because there is no way to solve the waterfall request problem of using modules (one module imports requires another module). Maybe some kind of standard manifest spec that tells the browser which parts of the code to load upfront and which parts of the code to lazy-load, but to generate that manifest in an efficient manner you would need at least part of what the bundlers do today.
Minifying is also somewhat of a hurdle, I guess it could be done at the CDN level on-the-fly+cache, but that is also its own nest of complexity.
SPA frameworks have a place, if anything I think they will become more prevalent, but I can foresee WASM opening the door for non-JS language stacks. However they will need bundlers as well and some languages are just not built around giving ways to minimize binary size and lazy-load code. Just try to compile some C++ to wasm, you end up with 10+mb .wasm files.
> Advances in the browser standards are slowly removing the need for most client side JS altogether
I probably wasn't clear enough when I said this.
If you're talking about waterfall requests in module loading, you've missed what I said and are likely sending orders of magnitude more JS to clients than you need to.
It's really worthwhile looking at all the new features in browsers over the last 5-10 years and asking yourself if you really can't do what you need just with vanilla HTML and CSS at this point. You can always sprinkle in a bit of JS to fill in some gaps if needed. My team usually has a 2-300 line JS file in each project. No bundlers or modules ever required at that scale.