(at least to certain target markets, especially younger millennial folks, who are more likely to be renters).Also, when looking at rental markets, I try to find places where it would cost substantially more to rent a single family home than it is to rent an apartment.

This is not to say there isn't subset of, say, Millennial renters who wouldn't pay a premium for this type of space, but I'd guess they would be in the city and/or on the coasts rather than in the flyover zone.

I did hear that population in Us is starting to go down so in future there may be less people to sell houses to as millennials are now a days not looking to start families.

Currently, an entire third of San Diego’s population consists of millenials, making it the second most millennial-populated city in the country.3. 

.- Too much pent up demand - Only 1 in 3 Millennials own homes.

I'm thinking that these will hold value well as far as the eye can see:Vacation houses, the sort coveted by trophy-hunting buyers, which are on the waterfront or similar "prime" locations in the warmer climates.Starter homes in demand by Millennials, will be in demand for some time to come. 

Think rust belt to sun belt (a super cycle), think east/west coast high company costs looking to relocate to Dallas to reduce employee costs and be close to key strategic transportation routes (DFW, interstates) linking coast to coast in a few hours.The long term trend of more renters has a lot of legs left (millennials, boomers), cost of a house is going up as well as higher rates so that will continue to keep people renting as well.  

I wrote a detailed overview of what to expect for the market here on Bigger Pockets which will quickly bring you up to speed:https://www.biggerpockets.com/forums/621/topics/396725-millennial-migration-to-sacramento-2017---here-comes-the-rushFor the Bay Area, I would suggest checking out their forums too here: Oakland, San Francisco, and San Jose.

From an article I read yesterday in: https://www.memphisdailynews.com/news/2017/feb/20/sector-by-sector-highlights-of-the-commercial-property-forecast-summit/Multifamily:Tom Grimes, MAA’s executive vice president and COO, said that millennials and their tendency to prefer rental properties are partly responsible for an increase in demand.

Sincerely,Millennial Renter