The meter has been standard for hundreds of years. Do you have evidence that it has changed in length?
Long distances were measured in one of two ways, both set against the standard meter length: a wheel or a tape. Have all these changed? Do you have evidence of that change?
If not, then you are playing games again. The 'What If' scenarios are not what I am concerned with. If you have evidence of this sort of change I am very interested. If it is simply an imagination thing, save it for telling stories around the campfire.
The length comparison to the wave length of krypton have remained exact. I think it is Krypton...
Michaelson used Cadmium.
At any rate, the scientists would certainly have known if there was a problem with changing length, even at that very tiny scale.
In the meantime, the change in the speed of light was so massive compared to any possibility and type of change in the standard meter, that this entire argument of yours about changing lengths is moot.