Fun fact: given that the meter is defined in terms of speed of light (and cesium frequency), "changing the speed of light" is a counterfactual impossibility, what is actually changing are some other fundamental constants.
If we realized tomorrow we had the speed of light slightly wrong, we wouldn't change the length of a meter, we would change the definition of the meter. We've redefined the meter thrice already.
If we realized tomorrow we had the speed of light slightly wrong, we wouldn't change the length of a meter, we would change the definition of the meter. We've redefined the meter thrice already.