  We quantify the extent to which future experiments will test the existence of
neutrinoless double-beta decay mediated by light neutrinos with
inverted-ordered masses. While it remains difficult to compare measurements
performed with different isotopes, we find that future searches will fully test
the inverted ordering scenario, as a global, multi-isotope endeavor. They will
also test other possible mechanisms driving the decay, including a large
uncharted region of the allowed parameter space assuming that neutrino masses
follow the normal ordering.
