Back this up with the 60 day notice served properly.Find out if there are any barriers he faces to getting the stuff out in a timely manner.

My question is, How sustainable is this run up in prices locally? 

I have found a new agent that I've been working well with and has been able to get me results in a timely manner and really seems to care about my interest and building a solid relationship.

If the answer is don't want them, then from a non confrontational manner immediately advise them you are selling the property and giving them a 30 day notice as you need to prepare it.I am sure Airbnb will not share you anything.However there is a person that is selling his course showing you how to airbnb a property without owning it.  

Additionally, due to some unfortunate family circumstances, my family had to sell some properties in a timely manner and try and 1031 the proceeds.

If you work in a professional manner, the tenants will believe you.  

and how does your company sustain overtime with these "lifetime" warranty as if the customer experience any problems with foundation, you will be called and you will have to provide the support. 

The key to avoiding the situation you are talking about, and rightfully so because it can be a dangerous situation is to buy properties that can sustain their income, in markets that support that sustainability.

A market is considered overvalued when home prices are at least 10 percent higher than the long-term, sustainable level.

So if your end product is 40k  lets break it down.. not a sales pitch or what you want to hear.your turn key company or provider is going to want to make at least 10k.. that's common in the industry.. that leaves 30k to do all this... your contractor putting it all together wants to make 3 to 5k.. so that leaves say 25k to put it all together.to have a sustainable rental.. you need New mechanicals new roof.. sewer scoped and replaced if needed up graded plumbing and electrical.. new paint and flooring.. cabinets and appliances and hot water heater.. this all cost at least 15 to 20k.. leaving you to pay 5k for the asset...