This is an interesting thread. A few comments I would like to add. First off the Mills Act is very cool, my brother bought a place near Balboa Park and the block that he is on has been going through the process of qualification. They are near completion but it has been a long process that started well before he bought the home.
San Diego never ceases to amaze me in terms of the diversity of the population. The amount of money in in the County is staggering, in terms of old money and new money. I think the compression (squish down) mentioned in MH and PL will indeed happen over time. I am toying with the notion that these areas may depreciate a bit quicker over time then other areas that are NOT LIKE them but offer better schools. I think that the demand for the young family looking for good schools far outweighs the professionals looking for an older nice home with a nice place to garden. No disrespect JP or any others. Thus I think that supply in places like MH or PL will linger longer.
I think that the supply of young people writing code for a Sorrento Valley company, while not inexhaustible, is much stronger and will continue to support the desired school districts.