A lot of the ideas here are good but of course there will be limitations on what is possible especially if we expect some decent online gameplay. If cool CAS features come at the expense of that, then i cant get behind any of it. That said, i remember being rather impressed with SC5's version. Dont know if it was because of how good it was or because i hated SC4's but i did enjoy the improvements a lot. Moving forward, if they can keep that CAS with just a couple of tweaks, i'll be happy. The major things i'd like to see are...
An option to remove that damned equipment break crap. So that we at least dont see it on our end of online matches if we dont want to. That feature is especially bad for CAS i think because none of those clothing pieces actually break or rip, they just come off completely. I guess that makes sense because that would mean an additional "broken" version of each item but it looks god-awful.
Divide shoulder and arm sections into two sides, so that we can design "heavier" or "lighter" sides on characters. This would go a long way even if they didnt add a single new item.... i would prefer this choice instead. A lot of the character's standard costumes are designed this way, such as Ivy.
I've noticed in some cases heavy armor for legs and arms have two versions of identical pieces that are just shorter or longer. Rather than doing this, i'd prefer they just give the option to exclude or keep the thigh/bicep portion of any armor changing it from the "long" or "short" variants. But that would obviously only apply for anything that appears to have visible "sections".
The last game had a weapon color edit which i was very happy to have but it was a bit limited because about half the weapons for any given character couldn't be edited including the standard weapons. This is something that would depend on which character you main. I imagine Taki players would care a lot less about something like this than say for example Yoshimitsu or Setsuka players. Anyone that has a large weapon or prop to go with it would probably appreciate this feature more.
This will come down to preferences of individuals but i think they should scrap a lot of the more elaborately designed equipment in favor of more basic, generic styles. Despite how cool a lot these things look, a lot of them only look decent as a set with the other pieces in its series rather than mixed with other stuff.