Running this sort of thing in a browser has become more and more feasible, but I still consider it fundamentally a broken idea. Even if the browser environment started to offer sufficient low level OS interaction (e.g. setting relative real time thread priorities, using SIMD correctly for metering and gain control, and lots more), I can only really see one reason to want to do this: ease of "delivery" of the software to the user.
Porting the 80+ libraries we use to wasm is no laughing matter, and it would be even harder to run plugins, since each of them would have to be ported by their respective developers (in the case of proprietary plugins. A browser based version that could not run Kontakt or Valhalla Shimmer would be a significant step backwards for most serious users.
However, you can already run Cardinal (the FLOSS-ier fork of VCV Rack) in the browser, so at this point it's anyone's guess where this idea might lead us.