The reality may be none of us know which way Bitcoin is heading, but the potential applications for Bitcoin technology are such that this (the technology) is surely likely to stay and to develop in new areas.
This is what I've been telling to people who are comparing bitcoin to the dot com bubble. The dot com bubble happened because back then people were thinking internet = free money, which it obviously wasn't, so the bubble had to burst. But the technology behind it stayed, and good dot com companies prospered because it was good technology and it is the backbone of pretty much everything we do right now.
The same applies to bitcoin, or the blockchain technology, to be more precise. Altcoins may disappear, even bitcoin itself may disappear in the future, but the blockchain technology is here to stay.
I don't get this notion of how "even bitcoin could disappear, but blockchain technology is here to stay".
Blockchain technology IS bitcoin, nothing else. If bitcoin fails, blockchain fails. The good news are: bitcoin will not fail. I have been here since the early days, I have seen conmen trying to sell smoke and mirrors of all kinds, promising the "new bitcoin" that never arrives. It is clear that at this point nobody is going to come up with a better implementation of the blockchain than bitcoin itself, because the alternatives are just small modifications not relevant enough to destroy the ongoing network effect of bitcoin by starting from scratch on an empty blockchain. It would need to be a whole new iteration of technology that is not even a blockchain (and no, IOTA and co don't cut it).