Plus, consider the source.
http://www.bbc.co.uk/news/business-15856116#TWEET33746
It's not an explicit "email is dead" but he was definitely suggesting email would lose in favor of messaging systems on social platforms (like Facebook).
Facebook COO Sheryl Sandberg echoed this in this talk: http://www.youtube.com/watch?v=Gm8NdNy4wOM
Even pg this week mentioned that email might not be the optimal tool and there might be a better tool to solve some of the problems (http://paulgraham.com/startupideas.html), and there is no shortage of email is dead posts and comments here on HN.
There is no possible way to infer that Mr. Graham was saying anything close to email being dead, simply that it's sometimes used for things that might be better handled other ways.