No one can predict what exactly will happen in the future. In the event of a nuclear war, they can turn off electricity and the Internet, no currency will have value.
That is so true, and thats why i own a safe at home stocked with gold, silver and canned food haha!
Diversify, never believe in just one thing as nobody can ever now 
Bitcoin can be called a bubble, because its price will depend on acceptance. It's now worth more than it should be because people believe in it, but it all could change within weeks.
If you look globally, then any currency can be called a bubble. People just decided that these pieces of paper have value. And everyone agrees with this. This of course is meaningless when there is a war
This is exactly my point so i completly agree.=)
Fiat money doesnt have a tangible value and a twisted supply/demand process. Cryptocurrencies might not have a tangible value, but atleast the supply/demand process is more stable as the supply is pre-set. This ofcourse has it's own challenges, but still is better then governments being able to offer neverending supply at will.