The future of altcoins will depend on the investor and if they are really worth it to keep up. Some of the altcoins are really not worth it and they are just copying others project and creating some changes on it.
I would say that the top 20 cryptocurrency are more worth it and can change the future when it comes to transaction and privacy of the investor.
clearly in the crypto world if altcoin is equipped with advanced technology it is more competitive and able to compete with altcoin while those left behind in development will sink.