In large part the structure of the theory itself and the nature of it's mechanism determines the bounds of the theory. Of course research and reflection may indicate that a theory's model or mechanism can and does explain more than first thought, and so the theory might be "extended," but the nature of the mechanism will again set effective limits.
Consider for instance the mechanism of natural selection. In its very nature it necessarily presupposes certain things. For instance that there is something to "select". So the entities to which it applies must have the property of superfecundity, or what Darwin called "ratio of increase". IOW they must produce more of themselves than the environment can potentially support. This means that you must have something that reproduces, and if selection is to have an effect on these populations of reproducing things then there must be properties of inheritance operative. The reproducing, environment dependent, superfecund entities that pass traits to offspring must also exhibit variation in inheritable traits if the mechanism of natural selection is to be applicable to them.
The only entities that possess all these traits: reproduction, inheritance, variation, superfecundity, etc are LIVING ORGANISMS. Therefore evolutionary theory presupposes the existence of living organisms. Their existence is a boundary condition of the theory.
Your last line illustrates the point I'm making;
Therefore evolutionary theory presupposes the existence of living organisms. Their existence is a boundary condition of the theory.
Someone who believes in creation would say it this way;
"Therefore creation theory presupposes the existence of a living creator. His existence is a boundary condition of the theory."
Without living organisms to start with the TOE is absolutely meaningless. This is why the Origin of LIfe Prize is so interesting. Someone is finally realising how important origin of life is to the TOE and openly addressing the issue. Whether or not it will change the boundries of the TOE or spawn an entirely new theory remains to be seen.
What do you think when you see the words,"The winning submission will likely provide both a novel and cardinal conceptual contribution to current biological science and information theory."?