In the immortal words of our ex-gubinator(with accent, of course): “That’s old news, man!”
Drinking a Copain Brosseau Syrah as I type. I’m with Ian - Central Coast, SLH, Chalone, SLO, Paicines, etc.
Can’t wait for the tasting room to open on the island!
Nevada
Do you mean Nevada County???
Lodi.
Sierra Foothills
Tijuana
No, the whole state. 
I am not sure that Lodi will grow physically but more and more fine wines will be made as more and more smaller wineries open. There is good fruit available at reasonable prices.
There are water issues from Salinas south.
I find it really hard to get around the road systems of those Northern Areas.
The maps kind of hide how difficult / time consuming traveling in that region can be.
I suppose that might hold back a little of the Napa like tourist expansion of some producing areas.
We once took some back roads back from Lake Berryessa, listening to our cars GPS, rather than our common sense, and those are really some sketchy roads. Same in the Jackson Rt 88 / Sierra Foothills area. I’d be really uncomfortable driving them at night.
====
I read the WS article where Beckstoffer pumps up the Lake County area, especially his Red Cliff vineyards. That seems interesting, maybe its even accurate.
It seems like a lot of “new” wine areas in California in recent years have really been old wine areas that people have forgotten about where there are still some really old grape vines - Zinfandel, Petite Sirah, etc. Where are there still unknown old vines out there. Find them, and you are likely to find the next hot area.
Probably not BIG, but with potential are:
The Channel Islands off the Santa Barbara Coast. Theres a small Pinot Noir vineyard in place now and as I understand it, its doing well.
Also, Hollister Ranch off the Gaviota Coast has potential. Olives are already being produced successfully.
This is a fascinating thread. Keep the thoughts coming!
I stumbled upon a fairly beastly tome online that touches on Beckstoffer’s Lake County and Mendocino vineyard acquisitions and his work renovating/replanting in these areas, as well as in Napa Valley in the wake of the phylloxera epidemic:
“The vineyard which we call Amber Knolls in Lake County should just change the face of Lake County in terms of premium Cabernet Sauvignon (116).”
“We’re very excited about Lake County. We planted new rootings, new roots, a new trellis, and new clones that have never been done there before. The grasses and the whole idea of cover crops and things–they haven’t done that before. This is the ground. It’s red volcanic soil, and it’s full of obsidian–absolutely full of obsidian, black obsidian (130).”[/i]
Wine Spectator California Wine Oral History Series:
Premium California Vineyardist, Entrepreneur, 1960s to 2000s: William Andrew Beckstoffer
(Interviews Conducted by Carole Hicke in 1999)
http://texts.cdlib.org/view?docId=kt3x0n99t8&doc.view=entire_text
It all depends on what you think of as a next big regions…great wines?? popular wines??
We see Lodi as a happening region as compared to what it was 20 years ago. Wineries are discovering special vineyards and working with the owners to create wines people enjoy and can afford. Twenty years ago people laughed at Lodi.
El Dorado county has lots of potential.
I just don t know about Humboldt and points north…perhaps there are special places to grow grapes…or maybe the Siskiyous. I have a cousin in Fort Jones …I wonder if he will ever plant anything.
There is an old saying that the market makes the wine. Perhaps when you are north of Ukiah you are too far from the market.
I agree with you on your points, Mel.
I would like to think that infrastructure that aid in the production of wine from grapes would appear naturally as the number of vineyard acres increase within any given region, but it appears that this isn’t the case…
I’m with Peter, Anderson Valley.
Such an interesting question - and one that remains ‘elusive’ as far as I’m concerned. If we are looking solely at ‘consumer knowledge’, I believe it somewhat depends upon where you live. If you live in NorCal, you are more apt to know a lot more of the wine regions from SF north because of media coverage than you are to know of the wine regions south of you. But if you live in the LA or OC area, you are more apt to know about Napa and Sonoma then you are to know about SB County.
Most ‘wine regions’ are known for ‘wine’ - if we were to play a name association game, here’s how it would go:
If I say, Napa, what’s the first thing that comes to most consumer’s minds?
If I say Walla Walla, what do you think the first thing that comes to most consumer’s minds?
Willamette Valley?
Paso Robles?
Even Lodi?
Now if I say Chalone, most folks will have no idea . . .
If I say Santa Cruz Mountains, most will not realize that there are mountains in the Santa Cruz area 
And if I say Santa Barbara, the first thing most think of is . . . the beach.
You also must look at the ‘politics’ of an area - how much ‘growth’ is possible based on the current political environment? How many acres of vines are currently planted and how much land is left to plant? Tourism?
Fun to discuss - and sorry for the trip down the rabbit hole
Cheers.
Sierra foothills has the land opportunity. Prospect 772 is making some awesome rhone wine near angels camp (south of amador county) and there really aren’t any other vineyards around. I’ll take their Syrahs all day for under 40 bucks.
Here in Livermore, there really isn’t any more room to grow. Housing took over years ago so now the city is all about preserving what vineyards we have left. Talented winemakers are coming in and while there are select high-level vineyards producing great fruit, there is definitely room for improvement as a whole.