I haven't heard anything new about this, but 3D-MVC support was announced when the Pi4 was released:
LibreELEC (Leia) 9.1.001 ALPHA with Raspberry Pi 4B Support – LibreELEC
Since then I have seen threads here and other places where the delay was about the new Linux core, video drivers etc.
Today I see a new comment on an old thread basically saying that it won't happen:
I am NOT complaining about the delay. I appreciate what I get! I would just like to see an "official" answer as to whether this is still on the roadmap for the Pi4.
I know the Pi3 build works fine, but it can't handle 4K and HD audio so LE for the Pi4 is the closest thing to a "play everything" player with the possible exception of the Vero-4K+. I bought one of those in the last couple weeks. It's a nice box, but no, it can't play 3D-MVC at this point. There is a buggy, older build of OSMC that theoretically will play 3D-MVC, but it didn't work well for me. It's a work in progress as well.
I'd just like to know if LibreELEC is still the king of the 3D hill!
Thanks!!