Well, many people in the party can inherit Mao's seat, and the rule of the CCP is a collective leadership, so I don't think this would prevent CCP from victory.
However, the heir might have a different ideology (not so populism as Mao), and have a much lower prestige, so the influence of USSR would be much higher, and PRC may not join Korean war, at least without (very) strong support from USSR (maybe PRC will send volunteers when USSR do so, or let USSR arms the volunteers).
The Cultural Revolution may not happen.