sure, you can change, but there's a lot of risk and loss of money involved.
Also, what about all the VCs, Wall street, and Merchant adoption. Will they follow you to your new beloved altcoin?
That's what i mean.
Facebook and myspace work well on their own (altough facebook has integration with many other websites nowadays, but back then it did not).
You can't just swap to an altcoin and expect merchants to accept it. What use is an altcoin with a 'better sourcecode' if you can't spend it anywhere?
That's why bitcoin will stay.
It's like, people switched from MySpace to facebook, but they still use HTTP to get there. They switched from hotmail to gmail, but they still use SMTP. Etc.
Since bitcoin has it's own protocol, that is by design not compatible with altcoins (as that would be like creating more than 21 million coins). Either the whole protocol itself will fail, or bitcoin will succeed, both as a protocol as well as a currency.
What is most likely to happen?
When it comes to a coin as currency nothing touches Bitcoin yet, And in my opinion nothing is really likely to. Network effect be praised, As you say it is Bitcoin's fate to succeed or fail. It is Bitcoin's game to win.
That said, I personally see a relationship with bitcoin and at least one other coin(s) which will offer features bitcoin should not have to. Privacy for one. In fact I think bitcoin NEEDS a symbiotic relationship with coins as well as services which compliment it and even facilitate it's dominance in the areas where it is designed to work.
The really successful altcoin will be the one that offers features bitcoin never can. It will actually protect bitcoin's dominance.