I still dont know why people counts 21 billion?? ahhhhh
Its around 5.4 Billion coins. The total Supply would be 21 Billion(that will be completed after years/decades of Mining). So basically, there are just 5 million coins in circulation.
Definitely it gonna boom as compared to Stellar/Cardano which have 6-7 times the price of electroneum.
Hence ETN would probably go to 1$ till April 2018 and 2$ around 2018 end.

So grab ETN. (current price is a few cents = 0.085$ ).