Realizing that you have a list the size of Matt's leg of features to implement and limited time... I thought of a cool idea. Or, at least, something I'd like and use, anyway.
What if there was a Playing Now feature that would display, in a layer over-top-of Playing Now (so, it would work over video, or over G-Force, or whatever visualizer you use), Lyrics for Music files and Music Videos, Description for Podcasts, and... I don't know, Description for TV Shows and Movies. It would have some sort of easy toggle on/off keypress and command in Theater View > Playing Now > More or whatever, so that you could turn it on and off at will. And, when showing Lyrics, you could use the normal Theater View sized font, and scroll it slowly, timed to finish with the track. (That timing wouldn't always work, but a lot of the time it would pretty well, and you could even fix it when it doesn't by adding blank lines strategically if you're a crazy person.)
That would be pretty cool.
It would be very difficult to implement third-party, because in order to add it over top of other display plugins, you'd need that "layer".