Thats why I think a decline will not affect the Bay Area greatly. 

To have flattish fall or even declines in winter is historically is historically not as unusual as it currently seems with the last decade (excluding 2020). 

Or is it indefinitely (I think some in this forum would love that haha)Does (or at some point in time) this population decline make California a better place to look at investing than other States? 

HELOC can be closed if value declines or credit declines...This is not a loan commitment just the general rules.There are also HELOANS and fixed rate seconds. 

Then just decline this applicant based on finding a tenant that better fits your (legal) criteria.

As my savings declined and I struggled to find a property, I couldn’t help but think about my mom.

It's been a declining program. 

In the event of a 40 percent decline, homeowners could see a nearly 10 percent increase, with the average residential bill reaching $5,723, assuming taxing authorities maintain their current levy rates." - Homeowners on track for property tax bumps thanks to office struggles

However, the home itself is priced on the higher end of my price range and will require $80K in rehab costs according to the seller who is an investor himself.A few low ball offers were already declined, and I'm not sure what those offers were.

To me 8% is worth paying off but you could just sit and hope rates decline too.