  Should dark matter (DM) axions be discovered in a haloscope, follow-up
experiments will be necessary to break the degeneracy between the axions'
coupling to photons and their local DM abundance. Given that a discovery would
justify more significant investments, the present work assesses the prospects
of ambitious light-shining-through-a-wall (LSW) experiments to target the QCD
axion band. Thanks to the excellent mass determination in haloscopes, we show
how to design HyperLSW, an LSW experiment with suitably aligned magnetic fields
to reach a wide range of well-motivated axion models and to determine whether
axions are the dominant form of DM in the Universe. In addition to presenting a
concrete plan for post-discovery experimental efforts, we also briefly discuss
complementary experiments and future directions beyond LSW experiments.
