Here's a thought:
Heydrich, perhaps, would resemble Laventi Beria. A highly ambitious, shadowy figure out to put himself on top. Heydrich outmaneuvering Himmler and taking his spot isn't that hard, given how insane Himmler is.
Himmler himself had usurped a great deal of power, essentially annexing the office of Interior Minister and its functions in 1943. At this point, he opted to seize power from the Nazi Gauleiters...which displeased Hitler and was humiliated by Martin Bormann.
If Heydrich were still alive at this point, perhaps this is his time. Himmler gets put in command of a bunch of soldiers in spite of having zero experience, while the Blond Beast now takes the reins.
Becoming Furher after Hitler's suicide in 1945 isn't impossible either. If Heydrich has Hitler's trust and Goering has discredited himself, Heydrich may well lead Germany long enough to loot the treasury and flee to Spain.