Is there anyone who know´s whether Ter2Blend will continue to be developed or not?
it dosn’t need that much more development! It is already powerful and has all of the features that you would need.
The only thing that is limited about it is the terrain size that it can import. Due to Blender’s geometry limitations, it is probably better that way.
BTW: The poly count limitation on the render and the mesh storage should be the first things to be worked on when Blender goes open-source. Dynamic allocation!