I have to say I don't think the article supports that at all. The study looks at a 2-year stretch and the changes in all but the hippocampus are still there at 2 years. Even friends who have reported "baby brain" don't claim it lasts 2 years, and synaptic pruning is not correlated with feeling foggy in any other study (and there have been a bunch!).
This article suggests a physical reason why that is so, as well.