It's not so much a show about bigfoot as it is a reality show about the people who devote their lives to looking for bigfoot.
If nothing else changes with regard to discovery, I don't see it progressing into season three without some significant alteration in cast or focus to sharpen its edge and keep viewers engaged. Otherwise it becomes a third season of the same crew stumbling around in the dark not finding conclusive proof.
If the Ketchum Study and Erickson Project effectively prove to the public that bigfoot exists, then the Finding Bigfoot crew will look like rank amateurs. They'll have been beaten to the punch by a long stretch. I predict that Cliff and Bo would stay on for continuity's sake and their likability, but that the remaining cast will be replaced by credible scientists whose purpose will be to meaningfully advance the investigation.
Now there's a contrarian approach the producers could take that might work. They could simply devolve the show further and blatantly turn it into a reality comedy about the misadventures of a group of people who can't quite achieve the goal others have proven possible. The show already has a slight slapstick element that seems to work for it.