from http://docs.kicad.org/stable/en/eeschema.html#introduction-2
There are two types of hierarchy…
The second consists in creating components in the library that appear like traditional components in the schematic, but which actually correspond to a schematic which describes their internal structure.
This second type is used to develop integrated circuits, because in this case you have to use function libraries in the schematic you are drawing.
Eeschema currently doesn’t treat this second case.
No, not yet. For this to be manageable/maintainable in code the developers need the new framework to be setup.
Should be possible when stable 5 (or sooner in the nightlies) comes around.
I guess it will be a long time.
The road map does not mention hierarchical schematics.
Looks like the developers will first change the framework.
From the Road Map:
Goal:
Use standard tool framework across all applications.
Task:
Rewrite editing tools using the new tool framework.