I love that freaking show. I too was bummed with the whole 'canceled>nuts>return>gone' issue, but I think they took it as far as they could within the realm of the small town, without resorting to wild and absurd storylines like with 'Lost'.
I suspect, and really hope, they will do a spin-off with some of the characters but looking at the broader scenario of a new American Civil War... now that show could be badass...