Nothing changes in what happens.
EVERYTHING changes in the stories we tell.

Einstein, photons travel & wave through an empty space which is distorted by gravity.
Tesla, photos are a waveform in the aether where every wave effects every other wave.

Einstein - events can only propagate at the speed of light
Tesla - events propagate via their mode. Sound waves in the air are slow compared to those in the water are slow compared to those in the ground. Further, there is (near) instantaneous communication across the universe.

And telepaths and quantum entanglement prove Tesla correct and Einstein wrong. There is no measurable time between what happens to one atom and the effects being seen in the other.

Einstein - we are trapped in our solar system with only a small bit of energy.
Tesla - we have infinite energy and can visit all of our universe.