I think that maybe eventually another coin with similar aspects will take over, unless bitcoin really steps up its game or side chains get good enough to keep it running despite massive adoption. Because that's really Bitcoin's biggest disadvantage, it can't process the amount of payments a world currency should be able to, and unless this is solved it's possible it gets replaced.
That's a classic shitcoiner viewpoint that's totally the wrong way around.
What matters, especially when you're dealing with code conjured out of thin air to begin with, is track record and trust. No one gives a shit about your one second block time if it's run by one server and maintained by one person and fifty people know about it.
That can be replicated a trillion times over. It's worthless before it got going.
What Bitcoin means cannot be replicated. It takes years and the efforts of millions of people. No way will enough people gather around another project of their own free will in the same way again. It's a once in a lifetime happening.
The incentive is there to make the dominant chain work, not invent a new one. Layer two stuff may deal with the capacity aspect. If not then something else may well come up.
I've seen Nano fans genuinely incapable of understanding why they haven't taken over the world yet. It's rather obvious if you think it through.