What's left to do for audio? Seriously? MC already can deliver bit-perfect PCM at almost any bit-depth/sample rate available, supports native DSD and DoP, supports WASAPI, ASIO, Kernel Streaming, etc., has lots of DSP options, has the WDM driver (which is working good now in the newer MC24 builds), is actually capable of passing through MQA to a MQA-capable DAC as long as you use no DSP and have volume set to 100%, has multiple memory playback options, etc. I'm not saying there's no room for improvements, as there always will be, but MC's audio support in general is pretty mature these days.
Honestly, at this point (until something actually worthwhile comes around for audio) all they can really do in regards to audio is improve existing features and add new stuff to those features. I suppose they just focus on what's in need of attention the most and where the majority of customers interests lie (hence these topics). Video and TV support are works-in-progress with constant features being added (Blu-ray menus and UHD support comes to mind as major additions made in the recent past). Panel is another work-in-progress which is becoming more and more viable as a JRemote/Gizmo alternative on non iOS/Android devices. Of course, there's also the MC builds for Mac and Linux which are still working towards feature parity with the Windows builds (or at least what's possible with Mac/Linux, which TV support may not be and DirectShow/Direct3D stuff like madVR definitely isn't possible).
Just my two cents.