Considering Russia and China are casually annexing territories, its pretty obvious this framework no longer exists. The UN made sense when the security council members had some incentive to use the UN system, but when their foreign policy is to circumvent international law at any opportunity, then its easy for them to sidestep it. Autocratic states ultimately can't work with democratic ones. Its unfair to expect one group to 'follow the rules' and another to go off willy-nilly when it serves them. There's no enforcer here, they're supposed to be voluntarily enforcing themselves and obviously that's not happening.
I won't even go into how easy it is for democratic nations to game the system either. Bush's run up to Iraq had all the hallmarks of the 'legitimate' UN: a debate, an airing of evidence, a vote, etc. Ultimately, it was just as hollow as an autocratic state annexing territory and telling everyone to piss off.
I suspect the UN has long fallen into pageantry and will never recover. It probably made sense to keep the US and the USSR from nuking each other, but today it lacks purpose and any real spirit of participation. It now exists to bully smaller nations who don't have a permanent seat in the security council, and because of that, it will never go away.