If we were to bring the same rational to the realm of cryptocurrencies, it is not likely any of the new coins (including Ether) is going to be successful in the near future unless there is an ecosystem around them. Building an ecosystem is unlike constructing a new building. It requires a vision and fulfillment of a need. So, if Bitcoin as a cryptocurrency is able to fulfill this need, where will other coins stand?
Because all cryptos are based on bitcoin, it is a simple matter of simply switching the bitcoin infrastructure to the new crypto. So Bitpay could start taking Ether, the bitcoin wallets could start taking various cryptos as well and so on. We've already seen the start of this with Coinbase adding Litecoin and Ether - they have 2.7 million users, who can now easily switch to another crypto if they want.
To bring up the MySpace/Facebook analogy again - both were functioning on the internet and were internet compatible, which is why the migration from one to another was so easy. If they were operating on a separate closed network, the migration would have been harder. Because the basic bones of all cryptos are the same, it is simple to adapt bitcoin's infrastructure to a new coin. The users are all on the same internet, they are all on the same social media (reddit), they are all familiar with how the basic wallets work, the basic structure of all the alts is the same, it is simply a case of using a different address...
This seems like a very gloom view. From this angle, Bitcoin must innovate or get replaced.