Fringe has struggled for years and has been under the threat of cancellation before only to be saved from the fire at the last minute. The network has openly admitted that it's losing money on the show, but in the past the DVR and Hulu percentages have been high enough to keep giving it a chance. Those days may be over.
While nothing has been made official, even the cast have hinted that they think the show may not make it past this season. I think everyone is trying to stay positive, but unless people start tuning in on Fridays, it's not going to be on for much longer. The sad thing is that it may take a while for the network to make the final decision and writers will be force to either scramble to put together some type of series finale or simply leave it as a cliffhanger and keep fans of the show wondering what ever happened to Peter, Walter and Olivia.