The only way for the equity and other asset classes to lose value rapidly is either the stop of liquidity (bank stop landing, people stop buying, or massive default) or all of sudden the money supply shrank due to governmental action like raise interest rate rapidly, etc.

Or all of the above.You may be a young guy working full-time in real estate and rapidly expanding your business.

The plan is to find real estate investors who do not have the time fully to find deals, or all the money themselves to invest in multifamily.

If any or all of those suck, your assignment fee will be minimal.

Not sure what kind of climate the property is in, but paying for part or all of your tenants' utilities can get expensive, since they have no reason not to (for example) run the heat full-blast with the windows open in January. 

Again there's no bad time to invest in real estate, unless the CDC decides to enact legislation that may "ban landlords from receiving rental income" or "all appreciation of real estate values to be collected by CDC" (sarcasm).

Some or all of the original investment in the rental property may be recovered through depreciation using Form 4562, Depreciation and Amortization.

Yes, Reggie Youngblood, a buyer can pay you part of or all of the assignment fee at the time of agreement or at closing.

Sometimes we'll do a broker to broker referral just sending them some or all of the commission; sometimes we'll send them a gift card for a couple hundred dollars; etc.

But I would make a suggestion on the payout.Assuming you have assessed that the lender will indeed agree to the short sale, or all lenders if there is more than one (many of the underwater homes are due to more than one loan) and that the mortgage company agrees the seller is in a situation of financial hardship...You will still need to realize that all lenders will have a clause within the sale agreement that the buyer or seller will NOT unduly profit from the sale.