You will continue to need the 3D Material Editor and the plugins. The tool has a nsbmd importer/exporter, which means you have to create the nsbmd yourself. Also, remember that the nsbmd you import must be texture-free; the btx files are linked to maps using the tileset value in that map's header.
Umm... I got a question is .NET Framework 4.5 the latest .NET Framework version?