Honestly, I’d be fine with the 5SP control scheme plus an added button for heavies (but with the option to still use A+B).
Basically SS6. ABCD + SP and allother buttons mapped as combinations (and taunt of course).
If they add a button for heavies then AB will probably suit some other function like it does in 4 and I think 3. Which I’d be okay with, although I like having mobility options tied to one single button because it makes them easier to utilize. It might sound whiny but for some reason things that require CD can be tough without a macro in 5sp because there’s little leniency in inputs.
I just hope they don’t have more than one button dedicated to kicks. The control scheme’s in SS1&2 are wasteful like that.
That’s exactly why I’d like a dedicated button for heavies. I’ve had too many wasted punishes in 5SP where I get A or B instead of A+B.
That said, based on their work on KoFXIV, I assume the window for 2 button inputs will be more lenient this time.
I would prefer:
A - Light Slash
B - Kick
C - Medium Slash
D - Heavy Slash
A + B - Dodge
As far as I can remember, B has always been Medium Slash. No need to change it up now.
Well, I have always mapped the buttons in this manner or something resembling Street Fighter or Guilty Gear depending on the game. Just to make it clearer:
 - Light Slash
X - Kick
/\ - Medium Slash
0 - Heavy Slash
 + X - Dodge
Then you just remap C to X. No need to change series notation.