Glee has this little habit of humanizing its bullies. Quinn Fabray earned our sympathies after that whole pregnancy ordeal in Season 1, and then again after we learned about her retconned backstory as an overweight preteen in Season 2. Santana Lopez won us over with her heartbreaking struggle with her own sexuality. Karofsky is a similar story: he lessened in jackassery after revealing that he was gay, and is no longer the one-dimensional bully we used to know. We've even warmed up to Sue Sylvester, especially after the death of her beloved older sister. So naturally, the show's going to need some new jerks.
Glee's third season will introduce three new characters, all (at least initially) antagonistic...
The first will be named Sugar, and is your traditional high school female bully: the narcissistic snob whose family fortune is exceeded only by her sense of entitlement (that's pretty cold).
The second is on the other end of the bullying spectrum: Sheila, a punk (presumably with a softer side hidden by her tattered clothing, coarse behavior and splendor of body ink.
The third is actually not a student, but a teacher: Nancy Bleithem, geometry, who (of course) opposes the inclusion of artist expression in the education system. Because really, if there isn't someone stifling our voices, what is there to sing about?
Finally, a non-vindictive character will be added to the cast in the form of a behemoth linebacker named Bubba. Bubba will step in as Mercedes' love interest in light of Chord Overstreet's leave. Chord really dropped the ball on this one. Not only did he leave Mercedes' and Sam's cliffhanger to be tossed to the dumpsters of aborted story arcs (along with Pam Beasley's art career and Liz Lemon's child adoption), but he doomed himself. Where in the world is there a more suitable working environment for someone named Chord Overstreet than on the set of Glee?
Overstreetless will the show go on, with these (and plausibly other) new characters and challenges, new highs and lows, new songs, new stories, new hours of strife...and new moments of glee.