Altcoins are mostly a mess. In terms of life expectancy, bitcoin has no competition at all. No one is going to willingly put their money into a cryptocurrency that has no realistic expectations to live in the long term, and bitcoin is the only crypto that has that trait: long term trust. So no, it will not get replaced by any other crypto as the king of crypto, it will reign supreme and it will be worth hundred thousands of inflation adjusted dollars.
I'm not so sure about that. Ten years is a long time, and who knows what the technical evolution will bring us.
Imagine a crypto currency backed up by a major company. Let's say apple would decide to make the step into crypto.
With their capital, their community and their advertising skills, they could easily create an altcoin the world has not seen yet.