No shortage should occur and here's why. In terms of enegy content, MTBE is close to zero. When the original tests were done, measurements were done related to pollutants per gallon of gasoline-- not pollutants per mile driven. In fact, the mileage for MTBE gas in CA is lower than federal reformulated gas, so supply would not be a problem if we switched to federal reformulatd gas.
But wait, it gets better. To comply with federal legislation (Clean air act) we must use either MTBE or ethanol, which is not produced here in CA. And their is no pipeline to get it here.
For more info on MTBE (Proven carcinogen) check link:
But there is no reason that we can't produce it here. - Just the cannery waste alone, which is now being dumped into the sewers, would produce more than three times as much ethyl as we need (actually we don't need any, but that's another story) for motor fuels.
It's time for the hype to stop.