Or how about this: the UN as it is currently set up, but with the most embarrassing and plainly counterproductive parts removed. Like, it's very hard for me to believe that any serious-thinking, politically-interested person could see, e.g., UNHRC and UNHCR as anything but deeply embarrassing and pernicious bodies that heavily taint the entire institution.
If that's the case, maybe the US should, instead of walking away like a sore loser, actively participate at these UN agencies and marshall its allies to more loudly condemn the likes of North Korea and China.