Gustav has the potential to eventually become a major hurricane, but currently only rhe GFDL is forecasting that sort of intensity. The 12Z HWRF has backed way off from its previous runs, apparently because of increased land interaction along the forecast path compared to previous runs. SHIPS has yet to forecast Gustav to reach major hurricane status and actually suggests weakening by around 4-5 days. None of the global models do much with Gustav and seem to be more interested in the other disturbances currently out there in the Atlantic.

Right now, it is mainly climatology (past history) and the GFDL that argue for Gustav becoming a major hurricane (assuming of course it does not get hung up over land). Both are compelling reasons to be concerned, but it should be noted that the forecast guidance as a whole is sending mixed signals about Gustav's ultimate fate.

Calling Gustav a "potential Katrina" is extremely premature. There have been literally hundreds of "potential Katrinas" in the last 50 years, but only one real deal.