Bitcoin has every chance of becoming the main (or one of the main) currencies of the world in the near future.
Mankind knows a lot of types of money. Before people started using paper bills, people used as money precious metals, cattle, stones, etc. We use plastic cards for everyday purchases now.
The main condition of money is that people trust it. Thats why the money of the future is bitcoin. The more people trust bitcoins and blockchain technology, the faster the crypto currency will become the main currency. I think that this will happen in the next 10 years.