since how long has been predicted the end of Bitcoin? at 1 dollar, it was swag; at ten, a bubble about to burst. one hundred, a Ponzi pyramid ...
Until now Bitcoin is always there, it made his way. I have no idea what will be worth a bitcoin in six days, six months or six years, but after more than 2-3 years of observation, I no doubt it gets more sustainability. And even if another system will eventually prevail, Bitcoin is and will always remain the first crypto-money free and decentralized.
Yes, bitcoin is now a sustainable currency, it came to stay for a long time and it will be always the number 1 because the bitcoin never stops to update itself, there is always things to improve in its system. However bitcoin isn't the number 1 yet for most part of the world.
Only when the adoption increases bitcoin will be on the top officially and when this happens I'm sure it will be top 1 for a long time.