Virtually throughout its history, and certainly in the 20th century, California has been known as the place to go for dynamism and growth. It did not become the richest, most populous, and most productive state solely because of its weather and natural resources. So it takes a lot to turn California around from growth to contraction, from people moving into the state to a net exodus from the state, from business moving into California to businesses leaving California. It takes some doing. And the Left has done it.
Until the Left took over American public education in the second half of the 20th century, it was generally excellent - look at the high level of eighth-grade exams from early in the 20th century and you will weep. The more money the Left has gotten for education - America now spends more per student than any country in the world - the worse the academic results. And the Left has removed God and dress codes from schools - with socially disastrous results.
America will nurture a new Muslim - one who can believe in Muhammad and the Quran but who abandons belief in a Shariah-based state and affirms the primary American value of individual liberty, which has not been a normative Islamic value.
America became a great civilization thanks to a culture based on the value of having to earn almost everything an American got in life. As it abandons this value, it will become a mediocre civilization. And eventually it will not be America. It will be a large Sweden, and just as influential as the smaller one.