The economy is a collection of segmented markets. Some 'segments' within this collection may collapse, but will always build themselves back up again. The economy is a self cleansing and self healing mechanism.
Barring certain currencies, there has never been an instance in human history of a financial market that has crashed and then disappeared entirely. The tech market plunged in the early 2000's but rebounded...
Between 1930 and 1970, gold lost a TREMENDOUS amount of value... but that market has also recovered.
The "world economy" is never going to "collapse" simply because there isn't a world economy... Just a collection of segmented markets that are designed to go through cycles
dont you think that some countries like the US for example are in big trouble compared to countries like the Uk and China?