I think you're wildly mistaken. I live in sf and know plenty of people in this community. Think of all the old people, the parents of 18-22 year old kids, the precedent it sets, etc. I'd be pleasantly surprised if that goes through, but it's not the first time it's been tried and I'd put $100 right now that it won't happen this year.
I’m 21 and my parents are in their 60s; we’re Judeo-Christian, we typically vote Republican, and we live in LA County. We briefly talked about this a number of months ago and I was surprised to hear them express that they might vote for legalization (mainly due to the additional revenue, less stress on our law enforcement system, etc.).
I don’t think legalization this year is as far-fetched as you make it out to be.
Yes, those people probably don't support it, but there isn't the loud controversy that you see over gay marriage. Most people are on one side or the other, but pretty close to the "meh" line, with probably more fervor on the pro-marijuana side.