In 2020 there will be another halving so i guess the price could really sky rocket. If not i predict are wider acceptance throughout the whole world.
Perhaps a smart country made it it's national currency.
It's too early to predict what would happen in 2020, IMO.
We're not even sure what will happen in bitcoin's price in the next minute, next hour, next day nor next month.
Although some people are using statistics and stuff to predict BTC's price, I doubt that within 4 years from now, there'll be no massive change about bitcoin. Maybe not the price that I think smth will change in bitcoin.
There is a good chance that the bitcoin is going to a higher amount in these upcoming years and that it will be much more popular in that year.
Overall I think there is also a good chance there will be another halving in that year.
If they implement that bitcoin debit card idea in the upcoming years, then surely the amount will sort of increase. But once bitcoin debit card becomes a hit, the price of BTC will surely skyrocket.