Failure by the Buyer to so notify the Seller and/or Seller’s Broker in writing, within the calendar days, shall constitute an election by the Buyer to proceed with the transaction.As @Nathan Gesner mentioned, an estoppel agreement is a great thing to get but I have rarely been able to convince a seller to get that from their tenants during a purchase and you could put yourself at a disadvantage when bidding on properties by requiring the seller to get this

You are subject to failure to file and failure to pay penalties.

All of them have Failure to Pays and other drama. 

That was shut down by my neighborhood with in months and I ended up selling for around $50k.Huge failure that was offset by the appreciation of my fourplex.

 I’ll start and feel free to brag about your failure.  

Is there really any other variation on this merry-go-round or certain failure?

If by real estate business you’re implying you have little or no money to invest but are contemplating using one of the guru inspired methods (subject to, “wholesaling” , fix n flip) to create cash flow, I’d encourage you to do research on the true success/failure rate of people who engage in these endeavors, the amount of money the successful operators spend monthly on marketing, and the real time commitment and knowledge and experience necessary for success.  

From my topical research, Tennessee doesn't levy any state income taxes at all, so, acknowledging that I don't have all of the information, you may owe no state income tax.Also, I would like to clarify that failure to qualify to a 1031 exchange would be irrelevant to you if you qualify for the 2 of 5 year exclusion.

For instance, I didn’t install grab bars in the shower, since more penetrations can lead to more failure points based on my experience.

Lots of things come immediately to mind:  Septic problems, a new roof, HVAC failure, lower-than-projected rents.