The Dark Energy Spectroscopic Instrument (DESI) is an ultra-efficient multi-object spectrograph installed on the Mayall telescope. DESI is capable of surveying ~2 million targets per month, and delivering redshifts in time for morning coffee. The DESI survey is now more than 60% complete, and so planning for future campaigns is beginning in earnest.
I will describe the scientific goals and achievements of the DESI "stage 4" experiment, with a focus on how DESI and DECam (and the Mayall and Blanco) differ. I will then present a proposal for an upgraded "DESI-2" survey, which will, in part, survey higher-redshift sources to probe early dark energy and the growth of structure in the matter-dominated regime. Finally, I will detail requirements to achieve a "stage 5" experiment, which could be met by upgrading Mayall and Blanco facilities and installing augmented DESI-type devices at each of these sites. I will outline proposed designs for such instruments, and the path towards making these proposals a reality!