The guaranteed positive effects of a Calexit:
-Cali’s 55 electoral votes are taken out of play, and millions of “liberal” (read communist) popular votes. (20 million?) This would pretty much guarantee Trump his second term, and possibly Republican victory even after Trump’s two terms.
-The rest of the nation is no longer subsidizing all the vile crap that goes on in Cali.

The potential positive effects of a Calexit:
-“Liberals” from around the country retreat to their newly minted utopia, while true Americans leave and shore up Republican power in other parts of the country. This is not guaranteed to happen.
-Hollywood movies could potentially be declared subversive/enemy propaganda.

The guaranteed negative effects of a Calexit:
-The loss of a huge amount of beautiful real estate and coastline, military/naval bases, farmland/food production, Silicon Valley, and the tax revenue from Cali’s citizens.
-Reduced access to the Pacific and we are no longer “protected” by ocean on both sides.
-A psychological/psychic blow to America.

The potential negative effects of a Calexit:
-“Liberals”, after securing the “annexation” of Cali to Globalism Inc., could simply leave enough operatives in Cali to govern, then send untold numbers of “infiltrators” back into other areas of the U.S.
-One or more other nations makes a play for control of the territory. (Mexico and China come to mind.) Then we potentially end up with a HUGE outpost of China right on our doorstep.
-There is no way to secure the new border between Cali and the U.S. The Commiefornia government allows untold millions more invaders into their territory and uses it as a base to further flood the U.S.
-California is apparently the world’s sixth largest economy, bigger than most other nations. This makes it a power in its own right. Independent of the U.S., it becomes an unfettered force for globalism, allowing globalism to retrench against the rising tide of nationalism.
-The attempt at secession creates further chaos/tension, and complications from the separation. It could potentially be the spark that ignites all out civil war.

Seems like a lot could go wrong. Better options might be:
-A full court press over the next four years to remove as many illegals from Cali as possible, and policies that encourage other immigrants to self-deport.
-Enlist millions of Americans from the deepest, most secure red states around the country to move to Cali and tip it Republican. (Combining this and the previous suggestion would create a powerful 1-2 punch.)
-Break the state up into smaller states, isolating the infected regions, reducing their electoral votes and freeing the “hostage” electoral votes of the conservative parts of the state.

I’m sure better minds than mine are gaming this all out as we speak.