They don’t usually do maps themed around minecraft biomes, those are too basic. However they could do a map based on charcoal sketches using alot of the blocks from this update or something similar.
Maybe a dead coral biome kind of feel BASED on this, but as @AnAbsurdName said:
doing a map exclusively biome-based is kind of basic. So making this map is a good idea, but there would have to be another theme other than the Pail Garden biome.
What about a structure using the new blocks? Look at the mansion map for reference. That map takes place within a forest, but the forest doesn’t really impact the game. Instead, it’s an esthetics thing. Maybe this map could include something similar, but instead, maybe have this structure abandoned and rotting away? I mean, all GI maps have their structures in relatively good condition.