The primary purpose of participating in the EB-5 program as a foreign investor is to obtain permanent residence. If you do not wish to obtain permanent residency for you or your family, then there are probably many other U.S. investment options you can consider. As an immigration attorney, I can assist you with the immigration applications and consequences of an investment, but analysis of the business viability is best left to another professional.
You ask very interesting questions which require an experienced EB-5 Attorney to answer.