That's a pretty bold statement. A billion years should be enough time to convert the entire galaxy into computronium and deploy all over it. Mind you, the author probably won't be around by then. Probably.
The article does imply that the sha's can't be cracked for those crazy time periods, though it seems to constrain that to the next generation of quantum computers. It's not stating that at no point in the next billions of years will a different computing platform come along that is capable of doing it. String computing, anyone?