There are no guarantees that anything will change.
But, playing the guitar is key! It won't "break in" just sitting in the case.
Its an inexact science. But I believe in it, I play my guitars to keep 'em loose.
-Gary K
Some guitars are so perfect they couldn't get any better.

Presumably any guitar could "age" in the case and change it's tone but that takes decades. I wouldn't except much change in a guitar rarely played and kept always at a perfect 70 degrees and 47%RH.
The other two factors, playing and environmental conditions are harder to separate as most guitars that are used "outside the home" may experience wider fluctuations in temperature and humidity.
My 1978 Fender acoustic also changed and got a better tone after several years of beating on it and wearing grooves in the frets but it also lived in the garage where I played it so no one would hear.
Gary's expression "to keep 'em loose" is not the first time I've seen it suggested that the process can revert (through lack of playing), that the wood or top becomes less responsive over time if not used. That's a slightly radical suggestion I've not contemplated. I play mine until they are junk, broken, or worn out so I can't say.