I am thinking again about this idea, which seems more and more appealing and useful.

In this scheme the rest of the world acts like a sidechain - x BTC are moven from the main blockchain to the sidechain, traded (as a whole) on the sidechain, then eventually brought back to the main blockchain.

Of course it's impossible to trace the movements of the x BTC on the sidechain.

TTBit did you implement the scheme that you described?