It is difficult to explain in English, but the question is: this plugin only for rendering of trees, grass?
For example, you know the game GTA - it happens gradually rendering the landscape - when the player is approaching objects. Can I use PagedGeometry for the same purpose? I hope I explained understandable
Paged Geometry is optimized for rendering batches of models, creating impostors that are rendered to a set distance. Thus for anything with identical models in great numbers, paged geometry is the way to go, not limited to trees. You can use it for rendering an asteroid field for example (I have, during my forays into it), or other semi-randomly placed objects with the same model, just rotated and scaled.
Note however that any physical simulation is up to your own code.
GTA4's engine is not dealing with a multitude of identical objects, but paged object loading in addition to LOD levels, and as far as I can tell some impostoring at the lowest LoDs. You could use it for the vegetation, rocks, lamp posts, generic objects with few problems, with the caveat that the physical simulation is up to you. Beyond that you will still have to constuct some form of LoD bias for the buildings themselves.
PagedGeometry was intended for use with trees, grass, rocks, bushes, etc., so that's where it will be most efficient. It's possible to use for other objects like houses, etc., but it would not be optimal - you could make a much better system if you wrote one specifically for rendering building, although PagedGeometry might be adequate depending on your needs.