Since the imposition of term limits, San Diego politics has been essentially a carousel - a politician starts out on one level, then slowly climbs his or her way up the ladder. Take Christine Kehoe, for example. She started as a San Diego City Councilwoman, almost beat Bilbray in 1996, then onto State Assembly, then State Senate. Each time, she's done an admirable job, and rewarded with voters. But she's also been able to take advantage of open seats as politicians above her got termed out. And following Chris is Toni Adkins, an admirable politician in her own right.
The one place where the carousel hit a wall was U.S. Congress. Unlike political offices for the State of California or the City of San Diego, federal office does not have term limits. As a result, Congressmen locally have held onto their jobs in Congress with both hands. All you need to do is look at Juan Vargas' scars from his campaigns against Bob Filner to understand this principle.
The other interesting factor is that until recently, the position of Mayor of San Diego was considered a crappy job. Seriously, outside of the usual suspects (Ron Roberts, Jim Bell, Steve Francis, etc.), few politicians would even conceive of running. And that's not a huge surprise, because the office of Mayor WAS a crappy job. The Mayor would set the Council agenda and act as the 9th vote on the council. While he/she would get credit and/or blame for the City's successes/woes, he/she couldn't do anything about it. As a result, San Diego never seemed to have good races for mayor, and also not surprisingly, the last four mayors - Roger Hedgecock, Maureen O'Connor, Susan Golding, and Dick Murphy - have not held public office after their terms ended. As a result, the carousel ends without many San Diegan politicians have a chance to move up in the world.
But two things have changed. First, the Mayor of San Diego is now the chief executive of San Diego City Government. The Mayor gets to do stuff, and not just look the part of the big cheese, but be the big cheese. The kind of big cheese that gets talked about for state-wide office, like mayor of San Francisco or mayor of LA. As a result, ten thousand people* are running for Mayor. Not only are they running for Mayor, but they're leaving their other jobs to run for Mayor. Second, redistricting has come to the Congressional districts, and these new districts with new lines and borders change everything. Darrel Issa, for instance, has to move back into the district he's represented for the past ten years.
So what does this all mean? The carousel has ended folks. For the next year or so, everything will be in play to a degree. Democratic districts will probably remain Democratic, and vice versa, but who holds these seats will be a crapshoot as more and more seats open up. Once epic contests, such as Filner v. Vargas I, II and III, are ending peaceably as Filner vacates his Congressional seat to run for Mayor. Or not. I don't know, you don't know, no one knows. That is going to make things interesting for the next few years because the rules have changed.
*All numbers are approximate.