Honestly, I think expecting the devs to do anything about this at all is what's unrealistic. And sure, The reroll is more likely, because it's easier.
But I really doubt the combination system would be any kinda of real challenge to a professional programmer. I think even I could code something in lua that would spit out new cape augs, given the old augs. And I'm no more than an rank amateur at coding. Sure you'd need more that just that. there's got to be a interface. A way of storing the augments on the traded capes on a NPC(Synergy and skirmish NPCs hold both your old and new augs for viewing, so there's precedent for this). A way to get back your first cape if you don't trade a second, etc. But I don't really see any of that as a massive challenge either. But hey, amateur. What do I know?
But since we're both dreaming of a change that won't happen, I say may as well dream big. If we get any improvement at all, I'll be happy. But I'd rather tell SE what I want, over what scraps I think they might throw me.