  The SuperCDMS Collaboration is currently building SuperCDMS SNOLAB, a dark
matter search focused on nucleon-coupled dark matter in the 1-5 GeV/c$^2$ mass
range. Looking to the future, the Collaboration has developed a set of
experience-based upgrade scenarios, as well as novel directions, to extend the
search for dark matter using the SuperCDMS technology in the SNOLAB facility.
The experienced-based scenarios are forecasted to probe many square decades of
unexplored dark matter parameter space below 5 GeV/c$^2$, covering over 6
decades in mass: 1-100 eV/c$^2$ for dark photons and axion-like particles,
1-100 MeV/c$^2$ for dark-photon-coupled light dark matter, and 0.05-5 GeV/c$^2$
for nucleon-coupled dark matter. They will reach the neutrino fog in the 0.5-5
GeV/c$^2$ mass range and test a variety of benchmark models and sharp targets.
The novel directions involve greater departures from current SuperCDMS
technology but promise even greater reach in the long run, and their
development must begin now for them to be available in a timely fashion.
  The experienced-based upgrade scenarios rely mainly on dramatic improvements
in detector performance based on demonstrated scaling laws and reasonable
extrapolations of current performance. Importantly, these improvements in
detector performance obviate significant reductions in background levels beyond
current expectations for the SuperCDMS SNOLAB experiment. Given that the
dominant limiting backgrounds for SuperCDMS SNOLAB are cosmogenically created
radioisotopes in the detectors, likely amenable only to isotopic purification
and an underground detector life-cycle from before crystal growth to detector
testing, the potential cost and time savings are enormous and the necessary
improvements much easier to prototype.
