It's far more than a dozen that simply packed up and left and there's also a whole slew of contributors, columnists, and other's associated with the publication that have quit and/or asked for their names to come off the masthead. Essentially anyone that was anyone has declared they want nothing to do with the publication anymore. Literally overnight a century old establishment is gone and not because it failed but because all the key people associated with it walked out the door. Even if you don't agree with everything said in the publication, it's a very sad day.
Those that left are preemptively saying that nobody was against advancing a digital strategy and pushing more content online, but what they are against is largely the incompetence of the new owner and the fact that Hughes seems clueless in understanding what about the publication allowed it to exist for a hundred years when others failed left and right. It's like someone bought the Royal Shakespeare Company and said "Shakespeare is so old and stale, I think we should like make action movies or something..."
Only time will tell, but Right now Hughes comes across looking like someone who stumbled into a lot of money by simply being at the right place at the right time with the right people--not because he's actually a skilled businessman. With The New Republic it's as if he thought "oooh, buying publications seems like a popular thing for rich guys to do... yeah let's do that and then do some cool Silicon Valley stuff with it... like I think I know something about that!" His husband's political campaign in New York this fall was equally a disaster. Voters saw through the fluff and saw someone saying "hey my husband has a lot of money and can pay for me to run for office... vote for me, it would be awesome!" Not surprisingly the voters weren't impressed.