what will happen to the businesses that were selling fireworks to general public?这个问题怎么回答?

you will get caught and go to jail.

Due to more and more restrictions around the world of using fireworks, the demand of such products in the market has been and will be dropping, and eventually will cause the firework manufactures' supplies being stuck in the inventory. So the trend of the manufactures that specilizing in fireworks will either be gradually out of business, or switching to become fire arms or weapon manufactures, since they already have the resource to manuafacture products with gunpowder.