There is always a reaction to every extreme political behavior. The elections of JFK and LBJ after the conservatism of Eisenhower. Then, as a reaction to LBJ, they elected Nixon.
Then, mass protests and the popularity of the hippies as a reaction to Nixon, his corruption and the war in Vietnam. The election of Carter.
The Democrats nominated McGovern and Mondale and the reaction was Reagan and HW Bush. Then Clinton came around for 8 years. Then the reaction against that by Dubya (Gore really won but Dubya got enough votes to be able to steal it. Then, Obama, followed by Trump (it was really Hillary who won) Then Rejection of Trump by Biden. Rejection of Biden with Trump (we know that Harris really won but Trump was able to get enough votes to cheat his way in. I think there will be a rejection of Trump and his pitiful economic policies and when the shit really hits the fan, maybe not until 2027 when the new tax cuts go through and the Rural areas lose their hospitals and totally go into poverty, there will be another reaction and the Democrats will be back in power. It will be much tougher because of all the Gerrymandering and election corruption.
There is the 40 year history cycle theory, but I think that the cycle is shorter than the 20 year cycles. Four Turnings:
Each 80-year cycle is divided into four distinct phases: "High" (confident expansion), "Awakening" (rebellion and social change), "Unraveling" (institutional decline), and "Crisis" (the "Fourth Turning"
.