What are the most in demand businesses in USA or in any country?
Air travel! Especially Southwest, even when ... no, ESPECIALLY when the economy is down, the seats are always full full full.
Apple ,Verizon sprint etc
In my opinion, the most in demand business in the USA or any other country are IT related businesses as well as oil and petroleum. Real estate is also a big deal especially when flourishing and the hotel business/food production.