A theory can be viewed as a group of related hypotheses that have repeatedly been tested and not rejected. Ultimately, theories cannot be proven. They are tentative entities, subject to modification and rejection. Stated simply, any theory could be wrong. Theories are not static entities either.
Science is dynamic and there is change within the paradigm and with theories.
Older ideas are rejected. As new evidence emerges, hypotheses and theories are rejected and modified. Actually, evolution is both fact and theory. A fact is a verifiable 'truth'. Evolution is a fact.