In this supposed 'greatest economy ever' I've had a few tenants within the past week tell me they won't be renewing because they can't afford it.

Noone has a crystal ball but rates supposedly are coming down in 2025 that should be enough time for you to do whatever you have to do if your credit is below 750. 

If you have a small multifamily (let’s say 4-family apartment) that has a main common entry door into the building, are you supposed to change the lock whenever any tenant moves and then give all the tenants the new key?

They left it alone a long time ago because it wasn't making them any money I suppose....I don't know but it's a crap show over there!!

Our current president is supposedly floating a policy idea of rent control to no more than 5% annually. 

Not sure how that's supposed to work. 

I suppose I need to at least try the Property management route first before I cash out and walk away. 

If they want to control these, how are you supposed to adapt to market realities?

Then you have "validate" the deals that were supposed to be pre-validated.

I think it is doable to self manage from afar but you are correct that you are supposed to have a local representative.