Lol, a side note: you're the guy who sold Spotify premium that stopped working right after. I didn't know any better because that was the first time I was posting on these forums and understand this whole new marketplace. I hope you were able to refund everyone.
In the next 50 years, BTC may be adopted. It may be dropped. There may be a new alt in it's place. We have no clue what it will look like in the next 50 years, if not the next 10. It's volatility makes it hard to predict where it runs. For now, I believe blockchain could be the future for the next decade or so.
But how do you define a blockchain? Is it a digital ledger secured by Proof of Work, completely permissionless and decentralized? Or is it something else like what the ICOs are doing? There is a big difference.
We must first know what a blockchain really is to predict its future, because in some definitions, anything can be a blockchain.