While I don't doubt that ultimately most transactions will become digital (and really, they already are), I don't think there is a blockchain ready to completely replace all transactions yet. Bitcoin certainly couldn't, it has too many problems (too slow, expensive transactions, etc). I certainly don't think such a thing is achievable by 2019 for that an many other reasons.
I think it will be difficult to have a single, exclusive world wide currency as long as nation states exist. I think there probably will be a worldwide currency but I don't think it will entirely replace national currencies. Kind of like some EU member countries (a few anyway) still have their own national currency in addition to using the Euro. I also think that blockchain technology makes it a whole lot easier for private currencies to exist, even if banks use that technology for evil. Even assuming Bitcoin was an NSA and/or banker plot, I wonder if they anticipated the volume and different types of crypto and blockchains that have ultimately developed as a result?
The thing about economic collapses is that if you keep predicting one for long enough, eventually you will be right because there will always be another one. If you can predict when, then you are on to something :).
What about once the Lightening Network is running at full capacity?
I predict next year ;)
I don't think lightning is a a cure-all though it is an improvement. It allows for almost instant transactions but there are still a few caveats. I still don't think it would be sufficient to replace the financial apparatus we have today. Plus there's the fact that it's potentially much more dangerous to have all your money locked up in bitcoin, particularly if you aren't technically savvy enough to keep track of your keys, keep them safe and backed up, etc. I'm not saying it won't get there, but I don't see it happening in the near future. I suppose banks could take care off all that for you somehow... There's going to be a huge resistance to a completely cashless society though, at least in some places.
Thanks for the clarification on the lightning network.
One thing I will say is that 'they' have had a long time to figure this all out and if they were able to trigger enough external factors all at the same time I believe it could be done, but they would have to be some pretty mega external factors.
Alien invasion mega ;)