As long as VSTs are native-only (which based on the low-latency nature of audio processing would probably never see a cloud implementation,) web-based DAWs will never replace locally-run ones. Most music studios airgap their systems anyway.
You could probably get alright performance running in the browser using webassembly. No idea if anyone's working on anything like that.
I'm curious too. From a quick search, I found WebDSP, "A client-side DSP library utilizing the power of WebAssembly".
https://github.com/shamadee/web-dsp
> WebDSP is a collection of highly performant algorithms, which are designed to be building blocks for web applications that aim to operate on media data.
> The methods are written in C++ and compiled to WASM, and exposed as simple vanilla Javascript functions developers can run on the client side.
..On further reading, they have functions for video and image processing, but not audio as far as I can tell.
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There's Glissando, "A web-based digital audio workstation using the web platform APIs (Web Audio, Web MIDI) and WebAssembly".
https://github.com/glissando-daw/glissando-app
They mention "VST support", but I cannot imagine how that's possible from the web.
The browser probably won't be good enough to replace Ableton (or similar) for a while but it is the primary medium for a lot of digital (interactive) artwork - for projects that use sound it's nice to plug a MIDI device straight into the browser.