I'd keep doing this indefinitely.

Income to rent %,  debt payment to income %,  include food assumptions, utilities, Gas if he has a car. Make

I plan to hold indefinitely at this point and refi at likely 10 years. 

In my jurisdiction I would leave my units empty indefinitely before I would rent to anyone on government assistance.

I am not sure what you meant my accumulating long term assets, but there are some syndications that have ten year and indefinite hold periods.  

Capital gains taxes can be deferred indefinitely through like-kind exchanges (swap 'til you drop).

@Matthew McNeil and @Jay Hinrichs, If you do a full 1031 (purchase at least as much as you sell and use all of the cash in your purchases) you indefinitely defer all gain and depreciation recapture. 

I could buyout the partner and continue to rent to the other business/tenant indefinitely and cashflow $5k+ per month until I sell in the future for $2mm+Which would you choose?

However, if you give them a blank check and tell them that they can pay you back, they will owe you indefinitely.

And the 1031 exchange will allow you to indefinitely defer the depreciation recapture and tax on gain (all of these on the US side of course).