I used to think coinbase is real exchange just like Gox. Store Bitcoin and buy/sell bitcoin. The purpose of decentralize is not depend on Gox like exchange. Just like I said if you don't want to goxxed then move in and out quick just like you suggested. It's not possible to get all or even 1/50 of the coins into one supernet but exchange like bittrex have all the coins.

The purpose of decentralize wallet like Supernet want to make people think real exchanges are evil

Another problem they will have is only trades among themself, just another way to kill a good coin. Say 1 coin have market cap of $1mill and a second coin is $4mil then soon both coins will be $2.5mil each. There is no purpose to join a Supernet if you want your coin to be alive, only dying coin would join.