From MonoGame's side people have actually already acknowledged how good libgdx is and wrote code and made guides like this: Port a 2D libgdx game to MonoGame
While this is a possibility I am seriously considering, it would be much nicer of course if there was a direct backend.
Since libgdx is very popular and everyone wants a route to PS4, this seems... not that bad.
At the least, the thread title is misleading... This isn't really about making games in libgdx, it's about getting rid of libgdx+Java and replacing with MonoGame/C#/VisualStudio.
You have a point that libgdx+Java doesn't have a good path to PS4, while all the other major engines including Mono, Unity, Unreal, etc do.
Hopefully, the RoboVM guys can flesh out a PS4 production path, like they have with iOS, and give developers options, and let people who want to use libgdx or jMonkeyEngine the choice to do so.