they won't be attacking like that
and they'll have bigger sights than them
it'll be either a physical attack on rootservers or a monster ddos attack
has happened before but when the internet wasn't as important
http://en.wikipedia.org/wiki/DNS_Backbone_DDoS_Attacks
unfortunately, the recent attacks on ipo and people like that shows individual site owners, governments etc aren't one step ahead of the badboys
most prob will never will be
taking out the rootservers is another thing, but if the right people wanted to, well, they certainly could cause temporary disruption. globally