What do we really need from an altcoins, what is the next big thing?
We have anoncoin, platforms for trading and smart contracts, tokens..
Where are we heading?
Bitcoin was something completely new, can we expect another one?
You should know that alt coins are used mostly to make more bitcoins rather than to be taken seriously. Though there are some coins who are much good and has a potential though bitcoin would stay as the major cryptocurrency than any other. Bitcoin is known as the king of all cryptocurrencies after all.
The only real coins that I respect are ones that address bitcoin's scalability limitations. After going through that entire list on coinmarketcap there's very few I'm actually interested in myself though there's likely a couple that I missed. All these coins that offer niche services are never going to take off because nobody is going to use them, and if companies do they'll just rip off the blockchain and make their own version because everything's open source anyways. Take care of the scalability first and you can throw those other features in any old blockchain. Not many coins are actually designed to address bitcoin's limitations.. my list is under 10 coins in that entire list of 300+... the most interesting is pascal which offers blockchain trim, and xtrabytes with the static nodes, and NEM for pure transactions per second but actually confirmed it runs at those speeds in real world situations, and there's a couple others I won't mention because I didn't buy them yet but I'll give you a hint... child chains.