Would love to see the ability for an instrument to receive MIDI on multiple channels. MIDI sends only a global pitch bend, and thus this is the workaround for some types of alternate tunings, or expressive instruments. There are free VSTs already set up for this such as Surge or Dexed as well as many top of the line ones such as Arturia Pigments.
As well would need to recognize the MPE standard pitch bend style messages which use another bit of MIDI data that is unused. (really I don’t know why the MPE guys didn’t just use this to send the note number rather than having to do this whole separate channel nonsense for their specifications, but someday 20 years in the future perhaps people will actually start using MIDI 2.0 and creating software that’s compatible and this will all be behind us. We can only hope!)