I just want to point out the difference between:

Blockchain - A number of records (called blocks) that are linked together and publicaly distributed for everyone to verify.

Cryptocurrency - A popular term used for all applications of blockchain technology - regardless if the project’s goal is to create a medium of exchange or not.

I would say that Blockchain is the next big thing - with applciations like:

Bitcoin, Dash and Monero competing with other currencies.

Ethereum building a massive virtual computer to execute smart contracts.

Ripple that aims to help banks transfer money faster and cheaper internationally.

Siacoin and Storj that are attempting to create decentralised storage platoform by utilising the free space on all our harddrives - while paying users who share their free harddrive space.

A comprehensive list can be found at coinmarketcap.com

Here are some of my thoughts in response to your question:

I don’t like to call the 1000+ different projects “Cryptocurrencies” because a lot of them focus on other problems, but this is the term people generally use - so let’s go with it.

All of these Cryptocurrencies / Open-source projects are fighting to apply blockchain technology in big industries (Currency, Internet of Things, Privacy, Exchange Platforms, Identity, Advertising, etc.)

If they are able to survive and are adopted by users, their underlying tokens will be in demand, causing it’s value to increase.

Since it is not clear which Cryptocurrencies / Open-source projects will be successful in a few years, there is A LOT of speculation, causeing A LOT of projects to be overvalued.

When thinking about Cryptocurrencies / Open-source projects, compare the situation to the famous Dot-com bubble in early 2000s.

Was the internet a big deal? Hell Yes.

Were most tech companies in early 2000s overvalued? Hell Yes.