Here's my dilemma I purchased a triplex in Boyle Heights California 4 years ago.

Hello BP, I have a dilemma .

Meanwhile the rest of the sale is tax deferred through the 1031.This doesn't fully solve your dilemma of whether to sell or not.  

He owns the house free and clear, but he hasn't maintained it very well the last few years as his health has declined. 

News flash, likely you won't be (in the health, ability, and mobility regards).

I think @Lee Ripma did a good job of summing up your dilemma, but instead of paying 1M and acquiring 50 properties to reach your goal, you could consider buying say 13 $150K properties that cash flow $200 month, spending $390,000 in down payment ($449,000 w/ closing costs) and then snowballing the mortgages so that eventually they are all free in clear.

If you're already going to be adding that tub/shower on the shared wall, maybe a half bath accessible from the common area would alleviate the "no first floor bathroom" dilemma without a ton of extra work... since you'll already be plumbing.

List/sold price is not the only indicator of health of the market, which is what I'm guessing you're trying to get at.

Taxes may be high in California but if they seriously go for that single payer universal health care they are talking about, it will definitely be worth it. 

Following this because I am having the same dilemma.