In theory, yes. Replacing old things with new things is the inevitable result of social development.
But for now it's unrealistic, and at best a replacement for bitcoin.
Other cryptocurrencies can only replace parts of bitcoin.
Yes.There will be more cryptocurrencies that will be introduce sooner but i don't think if they can compete with bitcoin's potentials.Or they will only live for months and then eventually die.Bitcoin has maintain its crown throughout the time so it only means that bitcoin has made its foundation stronger through the test of time.