Fuuuuuuuuuck. That is such bad news to me. I've been waiting for the announcement of new campaigns with baited breath like everyone else, but I couldn't really give two shits about the multiplayer component. For me I'd much rather hook up with some good friends on Steam and make a night of playing through a few of the single player campaigns. It's a much more enjoyable experience to me than heading online. I find the pacing is enitrely different and much less enjoyable, and you will often end up in a game where there are some obligatory whiney, annoying arseholes that are staple to all online shooters.
And will these new "2 complete campaigns" simply be the existing campaigns that aren't by default multipalyer enabled - Death Toll and Dead Air - that people are playing already anyway? That'd be a kick in the balls, let's hope not.
The best news there is the SDK release in my eyes. Even if Valve aren't going to put priority on creating new single player experiences there should still be an explosion of content from the community.