I just realised that the problem of the limited size of the Universe is isomorphic to the problem of how to survive the end of the universe, which I analysed here, but the escape routs described by OP are different, and more rely on acausal trade and simulation hacking than on physic manipulation.
I just realised that the problem of the limited size of the Universe is isomorphic to the problem of how to survive the end of the universe, which I analysed here, but the escape routs described by OP are different, and more rely on acausal trade and simulation hacking than on physic manipulation.