While there is technically no time limit on dictatorship, the CPC is approaching the longevity frontier for one-party regimes. Mexico’s Institutional Revolutionary Party retained power for 71 years (1929-2000); the Communist Party of the Soviet Union ruled for 74 years (1917-1991); and Taiwan’s Kuomintang held on for 73 years (from 1927 to 1949 on the mainland and from 1949 to 2000 in Taiwan). The North Korean regime, a Stalinist family dynasty that has ruled for 71 years, is China’s only contemporary competition.
https://www.project-syndicate.org/commentary/crisis-of-chinese-communist-party-by-minxin-pei-2019-09
