Relativity is unique and solid
Yes given some sensible symmetry assumptions (the laws of physics are time, location and velocity independant). You either end up with Galilean relativity or special relativity. There is a derivation of this in 'Wolfgang Rindler; Essential Relativity: Special, General and Cosmological'. I think he also describes this as being shown by an earlier authour but I read this book when it first came out and it is a long time ago now. Not only theoretically but observationally there is a massive weight of evidence for special relativity.
It would be very very surprising if future physics was not locally minkowskian at least on time and distance scales which are observable.
Biting the hand that feeds IT
