The X-Files: I Want to Believe was not exactly a smashing success at the box office.
Still, writer/producer Frank Spotnitz says he has hope for a third installment in this franchise. He explained why to MovieWeb:
The studio has not said yes or no. I think the box office, unfortunately, we got creamed in the theaters by The Dark Knight. I don't think anybody could've anticipated that was going to be such a huge, historic phenomenon. To be a dark scary movie coming out the week after The Dark Knight was not the best timing. I think there's life in the franchise still.
I think these are great characters. There's a date that looms very important in X-Files mythology, which is December 2012. I think after the DVD comes out, the studio will decide whether they want to roll the dice on another X-Files feature.
It's time to retire, Mulder and Scully.