Hi Ryano1989,
No, the exact list of ships will probably not be known until after Beta testing because Extremes is a new simulator, not an update of SS2008. It has a new sea model that requires some work to make existing ships work.
Most ships in SS08 will probably make it into Extremes, but Titanic poses some special problems that may defer its introduction.
As for new ships, some have been shown in videos such as the Green Peace ship and a Coast Guard ship.
Others are implied: For instance, realistic missions for Green Peace are promised, which implies the existence of whaling ships.
Understandably, VSTEP is reluctant to promise anything that might not survive Beta testing, or might not be finished in time for the estimated release date.
Around the end of this month, there may be a site and forum devoted to Extremes. More information may then be available.
Regards,
Marty