The are many 'laws' in the field of physics, a premise is not based on one law alone but encompasses all, as they can be understood, in totality. The laws of any system continue invariably to a conclusion. When matter is converted to energy you lose 'useable energy' in the way of heat lost. Thus it might not be 'nothing' in that sense but it will be 'nothing' in the ability to continue the conversion of matter to energy in the closed system. In the greater universal system, once energy and matter are used up, what do you have that is useable? Answer begins with a N and ends with a G. For the continued existence of the universe, in any meaningful sense, you would have to be able to convert 100% of matter to energy and back again. A difficult task.
Whether or not some TAZ members decide to go their own way should TAZ become non-autonomous, their existence is not TAZ as it was previously, nor would it be TAZ in the naming sense. It would be a new body of Zoners, bearing some resemblance to TAZ but being different at the same time, thus not truly being what it was before.
How to you propose that one describes 'good' in a world without evil? If someone has not known evil, they would have absolutely no manner upon which to base the 'good' that they enjoy. Unless someone else tells them. Which necessitates the existence of evil simply for the 'other' person to know.