And the reason Himmler dispatched his personal physician to Heydrichs care may have been to ensure Heydrich did not recover.
I’ve heard those rumors, the only thing that kept Heydrich in his position was that Hitler loved the guy, even thought the rumors of his Jewish blood would motivate him to be even more ruthless, to in Hitler’s words, “kill the Jew inside of him.”
I had also heard that on his deathbed, Heydrich was expressing remorse for what he had done, even going so far to request a priest to confess his crimes, even though he had left the Church years before.