I think the cancellation of "Angel" has done considerable harm to the chances of "Dark Shadows". After the hystrionic and sustained reaction its fans have put up, I suspect that the WB execs will be far more wary of the counter-productive aspects of picking up a show that brings an established fan-base.
I took a look at the primary "Save Angel" site and frankly it beggars belief - one day's campaign mission was to send Jordan Levin as many funeral wreaths as possible... And alarmingly many people with too much time on their hands seem happy to comply and fork over their money for the numerous other pointless campaign efforts.
After weeks of nuisance campaigns from these people, I suspect it's tarred all genre fans with the same brush. And with certain elements of DS fandom already planning "Save DS" campaigns, it looks like DS won't do anything to buck the trend. Personally, I find that whole rationale very difficult to follow... If we were midway through a season, fans would at least know what we were fighting for... But for the time being, the pilot is an unknown commodity, and I don't think protesting for something so vague does the show any favours. If you've seen it and passionately think it's the greatest thing on TV, then sure - but to me, begging for a reprieve just because it has the words "Dark Shadows" at the beginning simply isn't a good enough reason.
Groundbreaking it probably ain't, but the WB doubtless won't have Angel-esque grief waiting if it yanks "Jack and Bobby" after three weeks