I actually don´t think that cryptos will take over but they´ll coexist with our todays currencies. We won´t see the huge change happening just within a few years as the current system won´t be replaced this easily.
However it might be a real good idea to invest in coins that could still be around in 10 years. Don´t invest in something you don´t believe in! The weak projects will die sooner or later taking your investment with them...