Well the USSR was a democracy, not a monarchy. Malenkov became party head briefly because it was uncertain on how party Secretariat would be appointed, that's true. He would have been presumably who Stalin would have preferred. But the central Soviet didn't much care for Malenkov, so they formally elected Krushchev a few months later.

Who needs a succession plan when you've got the corn boy.

A great lesson to apply to all sorts of organizations. You actually have to put in time and effort to develop people and have someone capable and popular to hand projects over to.

Well it would've been better to let him retire after the war.