> And that's leaving aside the question of what it would affect. Elasticity/learning? Would it result in forgetting, or losing skill?

You can't get any of that from this study.

fMRI results are easy to manipulate into sensational news stories because deactivating a brain region sounds like a bad thing. Those brain regions are not always-on. Their activity declining during a task doesn't mean they start to atrophy or degrade.

The only thing it means is that those brain regions are not as active during that task. Tasks activate different parts of the brain depending on what they require. All of the extrapolations on top of this result are people projecting on to science they don't understand.