First, the fact that you think a nuclear exhange ONLY leads to total armageddon is amusing.
They will keep the nuclear exchange limited. Both men will get credit for "restraint" and ushering in a new era of world peace. But the suspension of the constitution that takes place will allow the WEF to reorganize western world governments under a single authority. Just as they have done recently in several countries, they will allow the public to write the new constitution (at least let the public think they are writing it).
Ok…that is a plausible scenario.