Which governing body determines these requirements?

The NAIC—the National Association of Insurance Commissioners—is the regulatory support organization created and governed by the chief insurance regulators in the United States.5.

Why someone willingly wants to work with a government agency that will slow down turnover, dictate rents and rent increases, and dictate repairs is beyond me. 

When valuing the property, focus on its net operating income (NOI) and use a cap rate that reflects Section 8’s stable, government-backed rents.

Any other government agency?

Beside the government regulation and insurance shutting down certain markets, STR industry will continuously grow.

Someone (government?)

As such, the plan will continue (i.e. it is not as if the Quest Solo 401k plan is being shut down and a new plan is started) but be governed by the new plan documents (which is why one needs to find a plan that supports the required features). 

Most of my renters are nurses, engineers, and tax payer funded employees (Government workers). 

Yes, the government pays the Section 8 rent timely, but more and more tenants are having to pay a portion of their rent.