The CMS detector currently includes three different muon detector types: drift tubes (DT) in the central region, cathode strip chambers (CSC) in the forward regions, and resistive plate chambers (RPC) in both the forward and central regions. Several upgrade projects are planned to maintain high data-taking efficiency with the planned running conditions for the high-luminosity upgrade of the LHC. These upgrades are designed to ensure detector longevity and increase redundancy, while mitigating rate increases and retaining sensitivity to phyics processes. This involves changes to electronics and infrastructure of existing detectors, and adding new detectors in the forward region of the CMS experiment. Plans for each of the muon subsystems are described here in the context of the Phase-II upgrade schedule of the CMS experiment.