California does have a massive illegal alien problem, but let's not get into conspiracy theory (I do wish Democrats support voter ID).
But yes, Trump's 30 point loss in 2016 was a low point and he will obviously do better there in 2020. Against Bernie, I could see him losing the state by 15-20 points due to Bernie doing worse than Hillary in Orange, San Bernardino, Riverside, Imperial, San Diego counties. Trump will lose the state of course, but reducing the margin could flip the OC congressional seats.
omg