Depends. Those who move to Idaho, Utah, Montana are not the same people who bid up the property and stay here.
The people who got out look at real estates different than those who stay but move further away (i.e. longer commute) or pay more by leveraging more (dual incomes, or at least 1 tech worker, look at real estate as asset and investments).
I don't think a $500k house in Idaho would appreciate much because there is always green field construction and nearly free land there. Your $500k house will be a $60k lot and $400k construction cost, and the structure will depreciate, the income level of the residents will lower as it age and higher income folks move to new neighborhood and selling to lower income folks, it will still appreciate due to inflation in general. Income wise, even if you are tech worker for Micron. You may make $140k the rest of your life in Boise vs $250k in San Jose (on the low end) vs $350k in San Francisco (on the high end). It is not the same lifestyle, just like you need to make $500k to live in Queen or $2M to buy a house in Manhattan.
In California due to land shortages in major cities (or in Jeff's case, LG or other SV area), the higher income neighborhood is in short supply so prices stays high, people then gradually buy into slightly cheaper neighborhood and "transform" it into a higher income neighborhood. A lot of people leverage more because to them it is an "investment" to get into the up and coming neighborhood. The appreciation is mainly due to the tech boom and the tech stock appreciation, and the shortage of land (it is a bay, with a lot of mountains, and the zoning / public hearing hell for rebuilding, and rent control, etc).
The lifestyle is different, they will likely cash out eventually or pass down to their children, instead of moving to Idaho early and invest in dividend stocks or index fund.
Yes, a lot of people are leaving, but a lot of people are still buying. The market is functioning as expected.
No. I have a friend (ex Southern Californian) that bought beautiful new house (over $500,000.00) in a Suburb of Boise. It has gone up $75,000.00 in a year. That's over 10%. The entire Western United States-has seen massive real estate depreciation in the last 5 years-partly driven by (in select markets) by Californians thinking they have won the lotto after crossing state lines. I have personally known six Southern Californians who have left the state.
I moved out 8 years ago. Paid cash for the house outside of Salt Lake-put the rest in the bank. Let's face it-anybody who owns a house in California in any half-decent area-with any money in the bank is a millionaire in California. That's something to think about-and gives one LOTS of options. It doesn't give you many options living in the state-but if you cash out it does.
BTW-you show great ignorance saying the land is "nearly free". You think the farmers-or mostly the children that the land was passed on to don't know what they have? Hardly. What's going on with land prices up in the Heber Valley, UT area is crazy. Or as I mentioned earlier-Star Valley, Wy of all places.