Change is in the Primetime Emmy air, even if it might not appear so on first glance.

Repeat victories for AMC’s “Mad Men” and ABC’s “Modern Family” imply that the big winners have already been etched in stone at TV’s top awards show. Thursday’s nominations could hammer that foundation, though past Emmy darlings will undoubtedly be back in the spotlight when the contenders are revealed at 5:35 a.m. at the TV Acad.

But this year’s crop of prospective nominees presents intriguing changing-of-the-guard possibilities, starting with scripted series.

The potential for a shakeup is significant on the comedy side, where some veteran favorites have fallen on seemingly harder times amid a growing group of alternatives both in broadcast and cable. Meanwhile, the sheer number of quality dramas on TV today — generating frequent salutes to a “golden age” — provide opportunity for new blood in the category.

Put it this way: Even if you declared all 2011 nominees ineligible to repeat, you could still have an eyecatching Emmy drama roster that included AMC’s “Breaking Bad,” PBS’ “Downton Abbey,” Showtime’s “Homeland,” ABC’s “Once Upon a Time,” FX’s “Sons of Anarchy” and TNT’s “Southland.” An abundance of choices paves the way for change.

Of course, the vets won’t give ground easily. Showtime’s “Dexter” has received drama series noms each of the past four years, losing the top honor to “Mad Men” each time. But as the oldest returning nominee in the category, it might be the most in jeopardy to an onslaught of contenders that include buzzworthy network-mate “Homeland,” the return of “Breaking Bad” from a year’s hiatus and the migration from the movie-miniseries category of PBS “Masterpiece” showstopper “Downton.”

Amid this, the watch is on for a third consecutive nomination for CBS’ “The Good Wife,” widely believed to be the only hope the broadcast networks have against their first-ever shutout from the drama race — in direct contrast to their sweep of the comedy series noms in 2011.

For its part, comedy offers its own share of uncertainty, with returning nominees “30 Rock” (NBC), “Glee” (Fox) and “The Office” (NBC) all having weathered less than ideal reviews for their most recent seasons. Whether those opinions are shared by Academy voters, or whether that group embraces such upstarts as NBC’s “Community,” FX’s “Louie,” Fox’s “New Girl,” ABC’s “Suburgatory” and HBO’s “Girls” and “Veep,” will make the category’s pre-dawn announcement must-wake TV.

Thanks to the departure of Steve Carell from “The Office” and the lengthy between-seasons delay that Showtime’s “Episodes” and star Matt LeBlanc took in the past year, comedy lead actor comes with two built-in openings for new blood alongside 2011 nominees Alec Baldwin of “30 Rock,” Louis C.K. of “Louie” and Johnny Galecki and Jim Parsons (the two-time defending champ) of CBS’ “The Big Bang Theory.”

Former supporting actor winner Jon Cryer of “Two and a Half Men” will try to make the leap to lead this year among a wide-open list of challengers, including castmate Ashton Kutcher, Will Arnett (“Up All Night”), Don Cheadle (“House of Lies”), Larry David (“Curb Your Enthusiasm”), Garret Dillahunt (“Raising Hope”), Billy Gardell (“Mike & Molly”), Joel McHale (“Community”), Adam Scott (“Parks and Recreation”) and the thesp who in many ways had to fill Carell’s shoes, Ed Helms.

A big factor in this year’s scripted races will be the absence of “Friday Night Lights.” One of TV’s ultimate underdogs, with its firstrun episodes landing on DirecTV for the final three seasons, “Lights” nevertheless won Emmys in 2012 for lead drama actor (Kyle Chandler) and drama writing (Jason Katims), along with noms in series and lead actress (Connie Britton). The show’s farewell, with Britton moving to FX’s “American Horror Story,” ensures turnover in the drama competish.

“American Horror Story” will be a story in itself, due to its somewhat controversial entry in the miniseries-movie competition — giving a category that has grown accustomed to change even more to reckon with. Several Acad members are no doubt preparing to rail anew against the idea that “AHS” can somehow be fairly measured against, say, HBO telepic “Game Change.”

Over in unscripted TV, all six nominees from last year — “The Amazing Race,” “American Idol,” “Dancing With the Stars,” “Project Runway,” “So You Think You Can Dance” and “Top Chef” — are in contention again, leaving open the question of which might be forced to make room for NBC’s “The Voice,” arguably the most talked-about show in its genre for 2011-12.

Balloting for the Primetime Emmys will end Aug. 31, with ABC televising the ceremony Sept. 23. For the Creative Arts kudos, balloting ends Aug. 24 in advance of the Sept. 15 event.