With the announcement yesterday, Zap2it's Laurel Brown asked if there are really more stories to tell. Series face this question every season. Bones has unfolded quite organically. Its most conventional seasons were 1-3. The WGA strike of 2007 shortened Season 3, leading Eric Millegan's character, Zack Addy, to be written off. This has allowed the show's tone to change week to week as different interns rotate into the mix.
Jack Hodgins has gone from a confrontational conspiracy theorist to a fitting love interest for Angela and an older brother figure to the interns. Angela has gone from a live-for-the-moment free spirit to someone comfortable enough to give Hodgins a place above the rest.
In Season 1, Booth was the instinctual man-of-action to Brennan's methodical woman of science. As early as Season 2, his inner character was explored through psychotherapy. I thought this would lead to incongruous revelations, but the process has been facilitated gradually by Drs. Wyatt (Stephen Fry) and Sweets, and Booth is now one of the most nuanced action characters on television.
Finally, Brennan's progress has been as carefully marked and pondered as you'd expect, yet, as with all the characters, I couldn't have predicted how she developed. That's why I watch the show. Each twist has been diligently woven into the series' fabric so it appears consistent and natural. A writer would say, "That's what I do."