That said, I don't expect the trend will reverse on a large scale, however much I may personally want to see it happen.

I've scaled to 9 doors and am in the middle of my first flip there.

One thing though , using an LLC makes you get Business Line Of Credit and also Business Credit cards which helps you scale.. you need to know though to manage good debt!!

The issue is scale.  

I have done several flips and I am trying to scale up and grow. 

Overall I think it is a good gameplan.One other option you might consider to scale faster perhaps is to buy the 1st two as owner occupied. 

Join a few of these and network and get ideas of  how to scale etchttps://www.facebook.com/groups/518424028676654/

The company I use has a sliding scale based on the age of the account, so they may charge 25% for an account less than one year old and 45% for an account that is six years old.

-Thinking long term, is this something I could scale to make my primary source of income?

I think you may have trouble getting a lender to admit that the property can be both an investment property (for your parents) and a primary residence for yourself.I think it would be much more likely that a lender would give you and your parents an investment grade loan.