Interesting, I seem to recal the original USAF plans were for up to three tanker programs:
KC-X, largely for more urgent KC-135 replecement which Boeing lost, then won as the KC-46
KC-Y, longer term follow on, which will augment above and also replace the KC-10. This new alignment between Airbus and Lockheed and might actually be better placed for this type of aircraft which would be likely be larger aircraft. But Boeing might have an edge as being “proven” and if the USAF does not have the funds or appetite for multiple programs.
KC-Z. Further down the road stealthy tanker.