Nuclear deterrence will not "deter" anyone. There will be some nut job out there who will use their nukes. You only need one bad cook to spoil the broth. Instead of giving everyone nukes, why not take all of them away and destroy them? , it's not that hard to be without them.

There is only one scenario I can think of where getting rid of all the nukes would be a bad idea. It's the reason why there is still some a smallpox sample being kept, even though it is practically extinct. What if someone else has it? In the case of nukes, no one knows what North Korea have. Then again, North Korea could not have nukes at all. But I don't think every country will agree to a No-Nuclear-Arms treaty, in particular the U.S. of A.