Infact MtGox are not smart people, why not create a secondary market, linked to MtGox. You have the nasdaq and you also have the OTC and pinksheet stock market in business world. So why not have BTC running on the main server, and then all the less important coins on the secondary server like some SHA-256 coins, BUT also some script coins, not all script coins are crap!!, Maybe crapcoin is crap
but i believe that for example Earthcoin, DOGEcoin are certainly coins that can be traded on the secondary market. Also smaller exchanges need to support payments in dollar, so that you can buy goes in currency and not always need to buy BTC first and then you can only start buying.... So MtGox think about a secoundary market, you will gain a lot of money...