While it's true that bitcoin is likely imperfect, it is also highly adaptable. Any alt currency with an attractive new property will probably just give cause to integrate that property into the bitcoin protocol. The alt currency would have to acquire critical mass at an astounding rate to surpass bitcoin at this point. And the more time that goes by, the less likely that already highly unlikely event is to happen.
I wouldn't be surprised to see some alt currencies with properties that give them unique functions that bitcoin has no interest in adapting toward. Your imagination is the limit here.
Yes. At the moment it is Bitcoin dev doing all the heavy lifting and the clone-coin issuers just copy Bitcoin's upgrades. Now, if a clone-coin came up with a fantastic new add-on, which was liked by the market, then Bitcoin dev could simply enhance Bitcoin using the new code. Unless, the new coin went closed source, but that would centralize it and cripple their growth. win-win for BTC,