With Bitcoin people get the liberty to exchange value without intermediaries which translate to greater control of funds and lower fees. Its faster, cheaper, more secure and immutable. It has a global acceptance and is less volatile than cash / local currency. Due to this feature, it becomes easier to conduct transactions across boundaries and online. It also allows exchanging value over the internet without any intermediary and gives its users access to their balance through a password known as a private key. So its private, secure and at the same time,open. Bitcoin has two things going for it that help significantly in this respect. Stability and entrepreneurship. Both far exceed that of altcoins thus far and will make catching up very challenging.
I agree that Bitcoin currently has the broadest ecosystem and currently, the highest utility. However, there are at least two alts that are better poised to be more useful going forward. Ethereum and smart contracts are clearly something that could prove to be more useful in the future and have far wider implications. It functions as crypto just as well as Bitcoin, but has so much more potential functionality that can be built on top of it. The second is Ripple, which has major backing from major financial institutions. This backing is going to be more valuable to people who want the integration of crypto with major financial institutions. It seems more likely than not to be that eventually Ethereum or Ripple, or both, will surpass Bitcoin in market cap.
I do not hope the the market cap of Ethereum or Ripple or both will surpass Bitcoin someday. Only the technology of both coin are better than Bitcoin at the moment. Both inherit the essence of bitcoin technology that builds systems, technologies that are much better than their biological father. That is the best thing for me.