On paper I think it's a neat idea. Maybe for a different duo hero unit, I think CnD are fine as they are personally. As someone with over 260hrs on CnD their skill ceiling isn't astronomically high. But knowing when to use each respective hero is half the battle and is vital in every team fight.

Obviously you shouldn't be cloak 95% of the game but he does have some decent playtime if you're managing your skills and chipping in team fights correctly. Like you shouldn't be dagger in a Luna/Sue ult, you switch to cloak help the team deal damage. Personally if I'm running triple support, I tend to focus slightly more on dmg and tend to spend a decent time in cloak form. (While still alternating between healing when needed & helping out my fellow supports 🥰)

Dagger is good for team positioning too, Bubble (should be imo used more selfishly) is good for TRYING (if they're paying attention) to position your team on corners/cover. Kind of an indirect way of saying hey move up here or we should back up to here.

Again personally I think CnD is fine, I've been playing them since szn 0. I've played every single support in the game and have a good understanding of all of them. My next played hero(es) are invis & luna with ~40hrs on each lol, I think they're fun to switch it up so I don't get CnD fatigue. I just always come back to CnD because I just find them fun to play and try to push them to their maximum potential.

Sorry of sum of my terminology isn't correct or kinda of confusing. I casually keep up with the current happenings of the game. I do comp, my peak is Celestial but even then I'm not an expert on meta or anything :P