The thing with MonoGame is that it was designed to be an opensource version of XNA, thus it doesn't have an evolution path.
FNA has done some experiments going beyond XNA 4 API design, however for the type of 2D games XNA was designed for, there is little else to add anyway.
FNA has done some experiments going beyond XNA 4 API design, however for the type of 2D games XNA was designed for, there is little else to add anyway.