  We use present cosmological observations and forecasts of future experiments
to illustrate the power of large-scale structure (LSS) surveys in probing dark
matter (DM) microphysics and unveiling potential deviations from the standard
$\Lambda$CDM scenario. To quantify this statement, we focus on an extension of
$\Lambda$CDM with DM-neutrino scattering, which leaves a distinctive imprint on
the angular and matter power spectra. After finding that future CMB experiments
(such as COrE+) will not significantly improve the constraints set by the
Planck satellite, we show that the next generation of galaxy clustering surveys
(such as DESI) could play a leading role in constraining alternative
cosmologies and even have the potential to make a discovery. Typically we find
that DESI would be an order of magnitude more sensitive to DM interactions than
Planck, thus probing effects that until now have only been accessible via
$N$-body simulations.
