I think the term "assets" in "all the worlds physical assets" doesn't mean all physical items in the world - including baskets of half ripe banana's, but things like durable, enduring, tradable wealth assets. ie: precious metals, collectables, land, art. Things that super producing wealthy people trade their massive inflow of currency for and therefore retain value.

There is only one asset you need though, and that is the same physical asset that Central banks hold that is not an IOU from another country. It is that asset only that will be able to be revalued and reflate the balance sheet when the currency 'assets' have burned to the ground.

http://www.ecb.int/press/pr/wfs/2011/html/fs110706.en.html