I, too, was disappointed when Flash Forward got cancelled. It seems that the really cool shows don't make a second season. I also liked "The Event" and that got cancelled too. I think though that Agents of Shield was renewed.
I predicted both shows would be canceled, because both were constructed based on a false premise: that audiences still wanted to watch shows that dangled "mysteries" in front of them that were really just annoying teasers. Lost really burned a lot of people not because of its controversial ending itself but because the writers explicitly promised that there were answers to all of the in-show mysteries and they would all be revealed, and then they reneged on that promise without any remorse, going so far as to tell the fans that they missed the point if they wanted those answers. Battlestar Galactica did the same thing, explicitly telling its audience that they had a grand plan for the show when they later admitted (and people figured out anyway) that they were just making it up as they were going along. Nobody trusts television writers anymore, and they are right to not trust them.
You can have mysteries and long-term plots, but you have to prove to the audience there really is a grand plan by letting them in on it periodically, and showing the level of consistency and direction you can only get when you actually have that plan. Flash Forward had a cool concept but they refused to go anywhere, and of course they couldn't use the book ending. They played with the concept but didn't really delve into it enough in my opinion, and that's what made it less compelling to general audiences. The Event even more blatantly attempted to exploit the notion of filling an entire armory of Chekov's Guns and never really firing them. Plus, its disjointed narrative really hurt in the critical first few episodes.
Interesting to note that Agents of Shield follows the ratings trajectory of Flash Forward fairly closely. I like the show personally and I think because its part of the Marvel Cinematic Universe it has some advantages in getting and staying on the air, but it really does need to create a solid identity for itself that isn't reliant on waiting for MCU movies to release to avoid spoilers. In my opinion, they need to make the characters more compelling by giving them more interesting stories, maybe by shifting to multi-episode arcs more strongly in the second season.
