I am a total layman, so I don't know. But if I understood it right, the nice final results relies on the use of Grassmannn variables which eventually cancel out

I am a total layman, so I don't know. But if I understood it right, the nice final results relies on the use of Grassmannn variables which eventually cancel out. Whether or not there is a path to non-supersymmetric theories, I have no idea. But even if it fundamentally requires supersymmetry, the jury is still out on whether or not the universe is supersymmetric even though the best versions have now been ruled out.