To be fair Jeff has replied fairly often to threads related to Hanzo reworks. There is a chance they’ll reveal who that “someone else” is.
About that post, I like to think it’s Reinhardt, since a major Earthshatter-related bug fix (which also affects Doomfist’s Seismic Slam) was announced. Despite what Overbuff currently suggests, the guy is in a terrific state right now.
Or Jeff might just be teasing hero 28, although at that point he’d be stating the obvious. There is no doubt hero 28 and potentially 29 are being worked on as we speak. Doomfist was around when Orisa was being tested internally.