I honestly don't get the optimism? Yeah, I want another season, of course... But they can easily cancel 5th season if ratings for TARAU4 will be bad, I guess. Or not? Because I think this means nothing so far... Everything is depending on good ratings of this season. They will not be filming another season when no one would be watching this one.
I mean they opened application for TARAU3 during season 2 airing, then canceled it, and then reopen it again 2 years later.