Advances in PCM (phase-change material) RF switches are presented with performance that rivals and even exceeds that of dominant RFSOI CMOS RF switches for wireless communications. PCM RF switch technology capable of sub-20 fs RON*COFF figure of merit performance is demonstrated that potentially revolutionizes future applications in the 30-300 GHz spectrum. RFSOI CMOS RF switch performance is currently limited to about 70-80 fs RON*COFF and may not be able to be improved by a necessary factor or 2 to 4 to be useful in the sub terahertz spectrum due to fundamental limitations. A comprehensive list of potential switch applications are presented to highlight the challenges relative to current capabilities and the significant potential for the future for 5G/6G and beyond for PCM RF switches.