Probably won't be since MIDI 1.0 solved most problems good enough. Even MIDI 2.0 after decades is mostly just increased resolution. The only thing I'm aware of that's really missing is polyphonic aftertouch.
> Even MIDI 2.0 after decades is mostly just increased resolution
The biggest change is that 2.0 is duplex which allows devices to discover each other on the same MIDI network. No more in/out/thru, it's all just one USB (or ethernet, or wireless) connection from a device to every other device. It also allows property exchange, which means devices can exchange semantic information about their configuration and parameters with each other.
On top of that, individual voices can now carry pitch and control information, while devices can exchange tuning information. That's a big deal for microtonal and non-western music.
It would be hard to undersell how monumental MIDI 2.0 is as a change from MIDI 1.0, but somehow the MMA manages to do it by making it out to be "32 bit!" (which ironically, it isn't - you don't get 32 bits of resolution in your CCs with MIDI 2.0).
Where MIDI 1 can more or less express the pitch and dynamics/timbre changes within a single piece of western music, MIDI 2.0 can express almost everything you do within a DAW these days, short of actual audio i/o.
Ah my bad (also not sure which document you're looking at, its in M2-104). I think I was confusing it with note on/off which only has 16 bits for velocity.
Poly aftertouch is in MIDI 1.0 -- it just isn't used much.
What MIDI 2.0 adds per-note pitch bend. That's a big deal, but you can also accomplish the same thing without all the complexity of MIDI 2.0 by using MPE, which is an extension to MIDI 1.0.
In a way, MPE is easier to deal with than per-note pitch bend anyways. MIDI 2.0 didn't bother to extend the 7-bit note number range, so you're still stuck with 128 notes. (This despite the existence of instruments like the Tonal Plexus H-Pi, which has 205 distinct pitches per octave, each with its own separate button!) That means in MIDI 2.0 you have to pick the nearest unused note and bend from there.
In MPE it's a bit easier because you can just grab an unused channel, pick the closest note to the one you want, and bend. It's a little more straightforward, and you know you'll never have to bend more than 50 cents either way.
So far, it looks like most of the expressive and microtonal instruments out there are using MPE. The only one I know of that uses MIDI 2.0 is the Lumatone.
MIDI 2.0 has attributes in note-on messages. Attribute type 0x3 gives you 7 bits for a note in semitones and 9 bits for a fractional part of a semitone, so a resolution of around 0.2 cents.
That's effectively just per-note pitch bend -- which is great to have, but it's still kind of problematic to only have 128 unique notes you can individually toggle on and off or otherwise control on keyboards that have more than 128 keys.
It's possible to work around the 7 bit limit, but it's awkward.
