There are already hundreds if not thousands of things you can do with bitcoins and practically nothing an altcoin can do that bitcoin can't.
Can the bitcoin network provide 6 confirmations of a transaction in 6 minutes? Nope, Dogecoin can. Can Bitcoin process 270 transactions per second? Nope, Litecoin can.
More parameter changes. Your argument is like saying we need to create a whole new internet because IPV4 only supports 4 billion IP addresses.
In fact the limit on size of the IPV4 address space *is* the main reason for migrating to IPV6. That's not going to happen overnight but it's happening (contrary to what someone said yesterday) and will continue to happen.
In the analogy, the general categories being compared are cryptocurrencies and the internet. Bitcoin, litecoin, peercoin, ethereum, etc. are implementations of cryptocurrencies. NPC, IPV4, IPV6, etc., are implementations of internet protocols. So Bitcoin is like NPC in this analogy. IPV4 replaced NPC for good reasons, just as IPV6 will eventually overtake IPV4 for good reasons.
Bitcoin won't be that hard to replace when the time comes. It won't happen overnight, but the hard part is getting exchanges and payment processors and businesses set up to handle crypto. Most of that infrastructure already supports multiple cryptos, not just bitcoin.
A better analogy is to social networking sites. The infrastructure that allowed people to use social networking sites cost a lot of money to build, and it took time to grow the market to the point where the general public was aware of it and starting to use it. And changing wasn't easy. If you had a geocities page and wanted to move to friendster without losing your content, there was no easy way to do it. But then once all of that was in place and the market was big enough, competition exploded because the infrastructure and public awareness were ready. That's what the future of crypto will look like, IMO.