Convincing site owners to give up their Google traffic, even for a day, and I would think it would take a week or more to make Google pay attention, now THAT's the problem.
No it would not, the index would adjust itself and deliver the results.
if you took all the print news media and the CNN's and had them taken off google, they ( google )would not give a crap.
All the blog's would report the news, and at the same time, google would end up penalizing those boycotting sites ( don't forget that 1 of the algo's signal is up time and the ability to venture into the web site. if that breaks on purpose the engine might lower your ranking, which at the end of the day is another revenue source ) LOL, didn't webmaster world do this every now and then, I bet the result's changed and recovery took some time ( I understand that it also got some positive industry results )
at the end I would love to see people do this, I'll enjoy the traffic.