Right now Obama has just under 19 months left in office, so if the Next President is Pro 2nd Amendment he or she can Repeal the UN Arms Control Treaty.

So what is the Probability that lets say Trump, Paul or Cruz if elected would Repeal it and if Repealed what would be the consequences if any?

I will take an educated guess that the UN would be really ticked off but they don't have the ability to do anything significant about it.