Based on what we know so far, here is my educated guess on how they will re-work the park. Based on Disney theme park design, this seems like the only logical way to make the park have a cohesive master plan and over-arching theme.
The front half will remain largely unchanged, representing Hollywood and serving as the gateway to your favorite Hollywood stories that you can explore in the back half of the park. It will probably be similar to Epcot with 2 distinct halves that sort of relate to one another. In the diagram, the orange line represents the divide.
The Hollywood part of the park will most likely comprise of Hollywood Blvd, Sunset Blvd, half of Echo Lake, and part of the current Animation Courtyard. Animation Courtyard could be themed to be the "movie studio" of Hollywood and would have Disney Jr, a rework Animation exhibit based on DCA's (after the preview center closes) and an expanded show in Mermaid's spot using Mermaid's theater and the old One Man's Dream theater.
Gone will be the Jack Sparrow building and exhibit space of OMD. In its place will be a landscaped pathway that leads from the hub to Toy Story Land. This will provide separation from the "Hollywood" part of the park and the "worlds of Hollywood" part of the park. The current office building and parking garage will most likely be staying. Done the road, in lets say 20 years, they will probably tear it down and create a new land taking over the office building, parking garage, and Animation Courtyard.
On the other side of the park, the entrance road will most likely be moved toward the canal. Indiana Jones' theater would stay (though they may change the show) as would the Hollywood and Vine/Primetime Building. Echo Lake would also be preserved. Star Wars Land would be built south of Star Tours, building out to the new road and over the current SOA/Muppets/Premier Theater.
In order to get to Star Wars Land, there will probably be a new path leading directly from the Hub to accommodate the new crowds. Gone would be the Commissary, Hyperion Theater, Sounds Dangerous, and Sci-Fi Dine In. Echo lake could be expanded to prove better thematic separation between the Hollywood part of the park and Star Wars. In addition, it would finally provide the studios with a large body of water like every other park has.
In the back, southern part of the park, there is room for 2-3 more lands depending on the size.
Red represents the main circulation of the park, with the front Hollywood half having a kind of upside down "V" pathways and the back half being a circle.