This oscillation in northern Pacific sea surface temperatures has a frequency of 30-50 years, so we'll probably be in the cool/dry phase for some time.
However, given the variable nature of climate and a host of other oscillations and trends that are occurring at the same time, it's irresponsible to forecast "extreme drought for at least the next decade" based on this single signal. For example, forecasters are predicting El Niño this fall, which is a (generally) stronger signal than the PDO, and is statistically associated with wetter weather in California.
You're definitely correct in worrying about the water situation in California, though. Population pressures, groundwater depletion, and climate effects all point to significant water resource pressure for the state in the foreseeable future. This will translate into higher food prices, as farming is a major use of water in the state.