As an owner of 3 SFR rental properties (all located in Tierrasanta) I watch the market like a hawk to gage rents and rental property inventory. My primary sources are Craigslist and the SDUT.
I noticed the number of properties offered for rent in Tierrasanta shift late last summer, soon after I rented out 1 of my rental SFRs. I believe what has happened is the flippers/investors stopped buying properties and offering them for rent, thus reducing the number of properties for rent.
I’ve been “landlording” since 1989 and I have NEVER seen such a dramatic shift in Tierrasanta rental inventory as this – I can’t speak for other areas. The demand side is strong too – I contacted various property owner/advertisers who confirm that demand is strong.
When interviewing potential tenants last summer 1 couple had just sold their SD house and wanted to rent for awhile, another couple same deal but wanted a short lease because they had plans to move out of state. The couple I eventually rented to were from out of state and had a combined income of >$150k but didn’t want to buy in an over inflated market.
In my other SFR, 1 couple with kids moved in from AZ and kept their AZ house with the intention of renting it. Now they are wanting to sell it and having a very difficult time finding a buyer.
In my other SFR, a couple sold their SD house at what they thought was the peak (back in 2002) and rented from me with intention to buy a SD house later when prices declined.

I have older friends who have been in the SD investor/ landlording business a very long time (ie buying Clairemont SFR repos for $18k in the early 60’s) and have witnessed market up and downs but even they are freaked out by what they see is the INCREDIBLE speculation of the past few years. FWIW they predict a 40% decline in property values.

My predictions (baring major wars, economic collapse etc):
Prices: median prices “sideways” – flat to down (~10% max) over the next ~6 years.
Rents: 5% – 8% increases for next couple of years only.