I think there's absolutely no need for a Kemper HD or Kemper 2 for that matter (just MHO of course).
Why? The Kemper is almost perfect. By now I have profiled most of my gear in the studio I co-own and I have to say that more often than not, the Kemper is 99% true to the original tone.
If you profile and refine properly (and there are a few things to learn and a lot of trial and errors here) you can get close to almost 100% to the original source.
But the added things in the Kemper (tube Bias, clarity parameter, definition, sag control etc.) plus the added EQ often actually further tailors the sound to your needs - in that it makes it even better than the original amp that was profiled.
I'm amazed each time how my favorite amps turn out after profilling. I actually prefer to play them on the Kemper than the real ones - as the Kemper is able to take the sound of the original and further fine-tune or polish the last 0.5% that I always felt could be imporved from the original amp tone.
Anyway, that's just my old ears saying how I feel about it.
Now, what's left to improve?
IMHO, not much. I would like a fast bootup time for live playing (so that I would not have to bring 2 Kempers just for safety to a gig). Although my main Kemper has never failed me yet, I can't imagine the horror of having to reboot it during a gig and waiting close to an endless minute.
Also, IMHO the FX can be improved (currently I would love a script phaser that sounds as good as my original old script Phase 90) as well as the reverb section. Not much more left to improve then...
The dual amp path - well I have never been a fan of that. IMHO the complications in balanceing EQ, phasing issues etc. of playing with 2 or more amps simultaneously are greater than the actual benefit of it. (but again, that's just MHO)
So for me - if they could sell an add-on DSP uppgrade card or something (that plugs into the existing hardware internally) that would just give a much faster boot-up plus a super fast system response in general (e.g. the remote change of a rig - audio changing instantly but the lights, display etc. changing later) would be ideal. But that's just me dreaming...