Giving Rust a chance for in-kernel codecs

I see what you're proposing, though that'd be an enormous amount of work. It'd be doing mostly the same thing as the DRM KMS/GBM/TTM/DRI3/etc transition, and although that has delivered solid improvements it's also been an ongoing effort for 20 years now.

With modern media hardware the main obstacle is becoming middle managers desperately trying to put ever more useless buzzword-chasing junk in the devices. Webcam utility plateaus at "looks okay in standard room illumination, provides the functionality of a point and click camera from 2005, does not eat cpu like a winmodem" and anything added past that is fluff and an extra point of failure the driver has to account for, even if nothing in userspace will ever take advantage of it. Sound cards went through the same blight at the turn of the century.