Scott Lay is a Democratic blogger who puts out the authoritative Nooner that's read by everyone in politics in California. He's come out with preliminary ratings for next year's races.
He has Republicans favored in 26 Assembly races and has 2 other swing seats. Republicans currently hold 25 seats and need 27 to deprive Democrats of their super majority. So the GOP should be able to pick up the 2 seats the party needs.
He has Republicans favored in 7 senate races, which would be a 1 seat pick-up. One of the seats he currently has as Lean Democratic has a Republican incumbent, while the other is the successor to the seat which is up for a special election. If Republicans win that seat, and Andy Vidak is an underdog, picking up 3 seats to end the 2/3 Democratic majority is possible.
He's optimistic on Republican congressional chances. He sees CA-7, 10, 24, 31, 36, and 52 all as swing seats, with CA-9, 26, 41, and 47 also in play. Some people here think I overestimate Republican chances, but I'm nowhere near as optimistic as he is on these seats. I could see CA-7, 10, 31, 36, and 52 as swing seats, although I favor the Democrat in CA-7, 31, and 36. Of the remainder, I'm only optimistic that CA-26 is in play.