This realization seems to indicate there can only be one coin that survives, unless there is some reason to hold the coin other than its relative rate of appreciation.
Back in the early 90s, there were probably tens of thousands of individual bulletin board services. Most towns had several, and there were about half a dozen national ones in the US alone.
Each one was its own walled garden, with little to no communication between them.
In the late 90s as flat-rate ISPs began to enter the market, all the walled gardens got steamrollered by the Internet's network effect.
A tiny, statistically-insignificant minority of geeks prefer the walled gardens, while the rest of the population like having a single email address that works everywere.
I already explained how this can be solved. If there is a liquid exchange between the altcoin and Bitcoin, then the altcoin is just as liquid and usable as Bitcoin in terms of transactions.
But the problem is if everyone wants to sell the altcoin, i.e. no reason to hold it, then there is no such liquid exchange.
It will be the same with cryptocurrencies. There will be one winner that achieves mainstream adoption, and a few toys currencies and that are kept alive by the few people who enjoy running them as a hobby and using them as testnets for new features.
It is possible that an altcoin could have strong anonymity that is very important to smaller percentage of the market, and that would be a reason to hold it.
There might be some other features that are important enough that some percentage of the market must hold the coin and can't hold Bitcoin.
Strong anonymity is something that if you need it, you need it, and not having it isn't acceptable.
Can you deny this logically?
Any other such features?