It is completely possible to render interiors and terrains with the new shadows and shaders. But according to the developers, that would take a long time for a tiny team.
.dts shape maps have been suggested for a long time, but it seems they'd like them to be made of bricks. That's possible too, but it's certainly not a good idea.
One idea is that we can use game-modes to create a unique .dts shape in the shape of the desired map. Gamemode_MapHills would create a unique .dts entity that looks llike a bunch of hills. The main problem with this is that it would be unbuildable unless it has very flat shapes.
The next idea is modular setpieces. It is also a good idea to have bricks like modular terrain, with textures on them, and placing them as public bricks. This idea is the very same I am using to recreate the Bedroom. Like the .dts idea, we can place these in a gamemode as public bricks.
I urge you, mappers, to see the latest update did NOT kill mapping, and to continue the great work you've all done to this game.