  We reconsider the discovery limit of multi-ton direct detection dark matter
experiments in the light of recent measurements of the coherent elastic
neutrino-nucleus scattering process. Assuming the cross section to be a
parameter entirely determined by data, rather than using its Standard Model
prediction, we use the COHERENT CsI and LAr data sets to determine WIMP
discovery limits. Being based on a data-driven approach, the results are thus
free from theoretical assumptions and fall within the WIMP mass regions where
XENONnT and DARWIN have best expected sensitivities. We further determine the
impact of subleading nuclear form factor and weak mixing angle uncertainties
effects on WIMP discovery limits. We point out that these effects, albeit
small, should be taken into account. Moreover, to quantify the impact of new
physics effects in the neutrino background, we revisit WIMP discovery limits
assuming light vector and scalar mediators as well as neutrino magnetic
moments/transitions. We stress that the presence of new interactions in the
neutrino sector, in general, tend to worsen the WIMP discovery limit.
