If every nation adopts cashless system, bitcoin will surely be the currency of the future days. The reason is that no other digital currency has got acceptance and popularity similar to bitcoin though lots of digital currencies have got existed.
Not really. Cashless system can mean a lot of things. The most basic definition of a cashless society would be a society where no paper money is used - and this is probably already pretty close, as the use of credit cards are already replacing cash in lots of aspects.
However credit cards are owned by commercial banks and based on fiat, and that's centralised creation of money. Bitcoin on the other hand is decentralised.