By almost all accounts, it appears that CA voters approved Proposition 8, which eliminates the right of same-sex couples to marry in the state, on Tuesday. Opponents of the measure still have rapidly fading hopes that thousands of uncounted absentee ballots will reverse this outcome, but Prop 8's passage appears substantially certain at this point. As has been noted widely, Prop 8's passage would not have been likely or possible without heavy involvement, both financial and otherwise, from the Church of Jesus Christ of Latter-day Saints. From my own observations, here is what I see for California Mormons, and the Church more broadly, in the near future.
1. A hollow victory- It seems fairly clear that Prop 8's passage will only delay the arrival of gay marriage in California, not prevent it. In the eight years since Prop 22, which was similar in language but was only a statute, rather than a constitutional amendment, almost 10% of opposition to same-sex marriage has fallen off. Furthermore, exit polls (which I know, incorrectly predicted a loss for Prop 8) indicated that the under-30 crowd overwhelmingly voted against it (67-31) while the retiree set voted in favor 57-43. This means that in another ten to twenty years, a large portion of support for measures like Prop 8 will simply die of natural causes, ushering in a more tolerant electorate.
Also, legal challenges against Prop 8's passage have already started. Their merits and prospects are debatable, but it shows that this battle ain't over. This could end up in SCOTUS, which does not look favorable for gay marriage advocates right now, but could look much more so in another four years. I fully anticipate that a pro-gay-marriage proposition will be on the CA ballot at the next election, followed by a responding ballot proposition depending on who wins the first. (No matter what side of the SSM debate you are on, I think that we can all agree that the ability to amend the state constitution based on a simple 50%+1 majority is positively ridiculous. A 2/3rds requirement I can get behind, but the purpose of constitutions is the protection of the rights of the minority. If a simple majority can change the constitution, it is not doing its job.) Which leads me to the second consequence...
2. A massive Mormon exodus from California- The next ten years or so are going to be quite expensive for California Mormons. If, as I alluded to in the first section, we see a series of back-and-forth ballot propositions on SSM in California every two years or so, few members of the Church will be able to afford to live in California (as if it were not hard enough already). They are facing: higher federal taxes on their $200K+ income (Obama), CA's already crazy-high state taxes (which may grow due to budget shortfalls), and a special "Mormon tax," which will end up being an extra ~$5-25K or more every couple of years to a "Yes/No on ___" campaign. It may finally get to the point where opposing gay marriage prevents California Mormons from building their food storage, having more kids, sending those kids on missions/to college, and saving for retirement. At that point, they will bolt for Utah and other points in red states. That leaves CA church units in the hands of 1) less-affluent members of the Church who were not donating to the campaigns in the first place, and 2) those who did not donate because of their support for SSM. Of course, this may end up being a boon to Utah and other "receiver" states since many of these members will be high-functioning members of society and the Church.
3. A brooding storm- The next few years are going to be very trying for members of the Church, both in California and elsewhere. We can break this down into several headings:
Missionary work- As I alluded to earlier, the vote of the under-30 set was overwhelmingly in favor of allowing SSM. In addition, people with any college education voted against Prop 8 by a wide margin. I suspect that something similar is afoot in other states, to a lesser extent in the South and Midwest, but still true in urban areas and college towns of those regions. Because the Church's crucial involvement in passing Prop 8 is so widely known (thanks Internet!), missionary work in this demographic is going to suffer terribly. Affluent college-educated folks are your future mission presidents, bishops, stake presidents, etc. and a whole lot of them will never give the missionaries a sympathetic ear after this.
Getting things done- In the next couple of years, whenever the Church wants to accomplish anything that requires any kind of public approval (building a new building, etc.) in CA or any of the more liberal states, they are going to find a whole lot of obstructions put up by those whose approval they need. I feel like most liberal-minded people looked at Mormons pre-Prop 8 and said: "well, they have some crazy beliefs but they seem to be genuinely good and kind people." Those days are over. We have become a "hiss and a byword."
The opinion of others- this could fall equally under the previous heading, but I will elaborate further here. The number of people I have seen on the Internet swearing an eternal hostility towards the Church, not because of Joseph Smith, the Book of Mormon, an embodied God, etc., but because of our advocacy on Prop 8, is absolutely frightening. I suspect we will see more of the attitude that this unfortunate commercial espouses. In the mind of SSM advocates, because of our open and public involvement in this political issue, everything we do will be put under the most rigorous scrutiny, and any criticism is fair game. We have already seen public protests at temples and meetinghouses, which is, in my mind, extremely unfortunate, but again, we are getting no more free passes ever again.
The membership- You might have read stories in the news or elsewhere on the Internet about people leaving the Church because of the Yes on 8 campaign. I don't have any personal anecdotes, but it seems like Yes on 8 is really going to tear apart the fabric of families, wards, and neighborhoods within the Church. My sense is that a lot of these people were inactive anyway, and while it is still a great loss, it is not likely to be felt in individual wards and stakes. But there is a "ticking time bomb" out there of members who have been hurt, either on their own behalf or on behalf of friends, relatives, and neighbors, and this pain is going to fester and stew. Some are just waiting for some other excuse to push them over the edge into inactivity or more direct measures to end their membership. If the "Yes on 8" campaigns repeats itself in the near future (see my #1 above) that will likely be sufficient excuse for many.
Also, any thawing on the SSA issue is over. Members who struggle with SSA but are trying to stay active and chaste are going to sense the increased hostility towards those like them, not because of Prop 8 itself, but because of the sometimes hostile and inflammatory rhetoric used in the campaign. They too are likely to bolt.
These prognostications are somewhat hyperbolic (and intentionally so), but not so far outside the realm of possibility that they should not be taken seriously.