That's a good point but at the same time I think that if BTC will ever reach "facebook popularity" somebody will have to look at the transaction numbers and find a solution (be it off blockchain or whatever other method) and there are many many other points like global legislation, security, stupid-proof wallets, etc.
We are still in early days and probably we won't see this happening in our lifetime

I disagree. Internet phenomena move very fast. Either up or down. If bitcoin is not facebook popular in 10 years, it will never be.
Yeah I agree. With the speed at which technology advances I think it is very likely we will either see BTC become widespread or see it die off.
Its been 5 years already if it doesn't become a phenomenon within 5 years its already doomed. Google, Apple iPhone, Facebook became massive well before 5 years. I guess you can say that bitcoin had regulation issues not really up until recently there was still no regulation.
Now with new coins coming out and the foundation wasting a year with a worthless update, it's time is coming nigh. Doesn't mean that the price can't go insane, it's just will never become mainstream.
As written before Bitcoin is just here to warm people up to cryptocurrencies and conditiom them to accept them, until governments come out with their own digital fiat currencies.
Bitcoin is a way bigger paradigm shift that a new product like facebook or the Apple iPhone.
Bitcoin is more like the PC, cellphones, or the internet, and both existed for decades before they really became relevant. The internet was around since the 70's but only became relevant in the mid 90's. Cellphones existed as carphones since the 80's but only became relevant in the late 90's.