Can we certain about supersymmetry (SUSY)?
According to John Ellis, "We are never going to know that SUSY is not there. ... I and my grandchildren will have passed on, humans could still be exploring physics way below the Planck scale, and string theorists could still be cool with that."
In the interview, Ellis mentions neither MOND nor Milgrom. Here is my opinion:
According to Witten, "... the orbit of a string in spacetime is two-dimensional (over the reals) and should be regarded as a complex Riemann surface. Physics without strings is roughly analogous to mathematics without complex numbers."
I say that Witten's statement is correct -- strings are the geometric completions of quantum probability amplitudes. How do we know that string theory is empirically valid? String theory with the finite nature hypothesis implies Milgrom's MOND, and there is no other mathematically plausible way to justify MOND. What good is SUSY? You need SUSY to do the "Einstein" part of the Einstein-Riofrio duality principle. Google "riofrio sanejouand". Use SUSY to embed the finite model of string theory into various infinite models of string theory -- this allows the expanding universe in which the observers are not shrinking to be (approximately) mathematically mapped into the non-expanding universe in which the observers are shrinking.