And good luck trying to liquidate your fractional share of a single family home.Sounds to me like the guy is going to stop making all payments on his freely renovated place as soon as you cosign, then you will be stuck paying his rent for him indefinitely or attempt to evict him.  

Over time, future appreciation improves the profit on the property your tenants are buying for you and that profit is taxed at a favorable long term capital gains tax rate (think really great IRR) or the taxes can be deferred indefinitely with a 1031 exchange (why pay taxes if you don't have to).Tax benefits and appreciation are really just the icing on the cake; cash flow is the only real reason to own rental property.  

You should consider classifying yourself as a real estate professional, this would allow indefinite deductions on your tax return. 

For the folks that take the time to treat their equipment properly, a good sprayer can have a nearly indefinite lifespan.  

use the process to buy more real estate and defer all tax and depreciation recapture indefinitely.

Isn't that a lot more logical and (much) easier to execute than leveraging assets and letting cash sit in a savings/money market account for an indefinite period?

If you move out of the property and change the use for investment and then use the property for investment purposes long enough to demonstrate your investment intent (there is no statutory holding period specifically but most folks feel comfortable at anything more than a year) you would then be eligible to do a 1031 exchange and defer the tax on the gain indefinitely. 

These would be my concerns:(1) you don’t know how long he’ll be in the house, and you’ll be stuck without cash flow indefinitely.(2) if he is able to pay some nominal rent, how much?

Until that's taken care of, you've got rats in the building indefinitely. 

Hardwood can last forever and can be resurfaced indefinitely every few years for ~.75/sf.