One thing I have noticed about the altcoins. Their exchange rates are directly linked to the exchange rate of Bitcoin. They depend upon Bitcoin for their very survival. Ether may be having a market cap of close to $40 billion, but it is incapable of existing independently.
Nonsense!
Bitcoin is #1 attempt to implement a decentralized payment system. It has enjoyed enough being the first attempt and a successful one at the same time (a very rare condition) but naturally its success is relative and it is not the end of a technology. Altcoins, understanding the situation, has come around prepared for the competition with features like scalability, anonymity, speed, smart contracts, ...
From a long term point of view, obviously, being #1 attempt is not a strong enough leverage to remain on top, improvements should be made but btc can not and will not handle improvements, it will fall sooner or later.
Bitcoin won't disappear, it won't even lose value, it will become somewhat obsolete by performing less transactions (actually it has already lost the transaction volume battle) becoming a simple digital asset, and nothing more.
A replacement for fiat currencies and daily payment practices. Ethereum? Zcash? ... they have chances, btc? Noway!