It seems clear to me at this point that the cryptocurrency revolution is now bigger than Bitcoin itself. Years ago, I saw three long-term outcomes: Bitcoin being king and altcoins dying on the vine, Bitcoin being one of innumerable blockchains in use, and cryptocurrencies in general failing to gain adoption. I'm scratching the first outcome off the list, and my pen is hovering over the last outcome.
That's speculation on the level of Bitcoin taking over. There's no reason to value altcoins over sidechains, for example. We don't know what the future will bring, only that large economies can't take place wholesale on a blockchain. But whether transactions denominated in Bitcoins will be popular is anyone's guess. Surely some better technology will come along, but it won't be altcoins as you know them.
> Surely some better technology will come along, but it won't be altcoins as you know them.
There's no reason to value sidechains over other coins. Better technology will come, but it could come in the form of other coins.