However, another well watched show, Alias, lost a ton of viewers in season 3 because they took 3-4 weeks between episodes sometimes, then went with the 1 new episode per week for their fourth season, only to backtrack and go back to their idiot broadcast schedule for season 5. Needless to say, their number of viewers has fallen totally off the scale, and this is most likely its final season.
I assumed Alias lost viewers because it just went shit and made no sense, as if they were making it up as they went along (which would explain the gaps between episodes)...
The biggest hurdle they have is the timeline they are proposing. I'm assuming they are going to finish episode 1, release it, then start on episode 2. TV shows don't do that, they film and complete multiple episodes before the first one is shown. SIN episodes will have the best chance for success if wait until they can release them all within a year. (That may mean release episode 1 when they finish episode 3, or it could mean releasing episode 1 when they are half way done with 5.
They havent really disclosed exactly how much content is complete, but I doubt they've done more than episode 1, given what they've shown us...