Oh, no... Not that thing again.I don't want to go too much off topic but to quote xkcd "More harm has come from people decrying societal decline, than societal decline ever has."
I like how Carr's own sentiment mirror the sentiment of people who thought books will stop people from remembering things. And he wants us to return to books?
Ugh, no. I suppose you've extrapolated quite a bit from the title. Carr thinks the benefits of the internet are massive, undeniable, and (probably) inevitable.
He's simply pointing out evidence that our tools change the way we think. He makes the same point about clocks, maps, books, etc.
The book has zilch to do with societal decline in the sense you mean it.
I'm reading it right now and, if nothing else, can totally relate to "I can't concentrate on things very well anymore" feeling.