If they seamlessly integrate iMessage features with rcs then I would call it solved

ie if iPhone users can react to messages, include rcs users in group chats with iMessage users and all share HQ photos, send voice memos, and whatever else without missing any of the features because the other person is rcs or because one rcs person in a group chat causes the entire group chat to be downgraded, then the only remaining difference is the color of the bubble so the only people hating on green bubbles will be those who do it solely because of the color and not because of any loss of functionality, which I think would be so few people that it would be a non issue