Disagree. Dreamworld is already pretty damn big. there is plenty of space inside the current park envelope for them to expand without needing more.
Thunderbolt. Troll's Village & FlowRider. Rocky Hollow. There's also opportunity to do something with the Murrisippi and the island as long as they preserve the waterway. As time goes on you start to see other attractions due for refurb or retirement - Motocoaster is 18 this year - maybe they invest in a retheme and refresh to give it another decade or maybe they decide to pull it in favour of developing the plot into something else? (lord knows the dead zone between Giant Drop and Main Street Station could use something to liven it up). There's also potential to slip something inside of Taipan's footprint, or Buzzsaw's plot, and cyclone\gold coaster can't have much more life left in it, surely? I'd love to see them take the convention centre building and turn it into an indoor attraction complex with an ocean-related theme to tie-in to Ocean Parade.