I don't see any of the competitors having much of a chance at disrupting the natural monopoly that mtgox is sitting with. Competitors would need to significantly step up their marketing costs to begin eating market share.

As someone noted all the other exchanges failed when they tried handling the trades which fled gox when it shut down.

To compete with gox you are attacking a defensive market incumbent. You need a factor 7 of funding of the incumbent to have a decent shot at winning. None of the other exchanges is currently close at having such resources. The best they can do is to attack as an underdog and try pick off accounts from gox at a slow pace. Will take years for such a transition at best.