The many-worlds interpretation is a theory for explaining our observations from quantum experiments. It posits that reality consists entirely of a universal wavefunction that deterministically obeys the Schrodinger equation (or some other wave equation). The apparent probabilistic nature of quantum experiments is normally explained by appealing to a non-rigorous concept of macroscopic worlds where each possible result of a quantum experiment happens in one of these worlds. However, "worlds" are merely convenient abstractions, and are not fundamental to the theory's main statement.
The other names of the many-worlds interpretation include "the relative state formulation", "the Everett interpretation", and "the theory of the universal wavefunction."
This question resolves positively if by 1/1/2050 a poll of professional physicists with at least 100 responses reveals that more than half accept the many-worlds interpretation of quantum mechanics, as I have described above. The results from the poll must be published in some reliable document or blog post, and must not be informal. If no such poll is released by 1/1/2050, then this question resolves negatively.
Here is an example of a qualifying survey uploaded to the arxiv in December of 2016. 39% said they preferred the Copenhagen interpretation, 6% the Everett interpretation, 36% had no preferrence.