Robert Greenblatt poses in the press room at the Broadcasting & Cable Hall of Fame 27th anniversary gala in New York. (Andy Kropa/Invision/AP)

WarnerMedia is getting narrower in the hope of getting bigger.

And several networks could change as a result.

The company, which controls high-profile entertainment properties including HBO and the Warner Bros. film studio, is reshuffling divisions and executives as new owner AT&T aims to keep pace with better-heeled competitors in a direct-to-consumer age. The reorganization could result in a large number of layoffs among the tens of thousands employees, though the company did not enumerate those plans Monday.

The most significant change comes as HBO and parts of Turner Broadcasting, historically two separate divisions, have been brought together under newly hired executive Robert Greenblatt.

Greenblatt, AT&T said, has been hired for the newly created role of chairman of WarnerMedia Entertainment and Direct to Consumer. The company hopes the former Showtime and NBC executive can increase and tailor content on both HBO and TNT/TBS/truTV for a planned new streaming service.

His appointment follows the announcement last week that Richard Plepler and David Levy, who headed HBO and Turner, respectively, will be leaving the company. In addition to the TNT-TBS axis, Greenblatt also is being handed a large degree of oversight for the company’s planned new streaming service.

The question of these networks’ futures will be one of the most closely watched in television in the coming months — particularly at HBO, which first inaugurated, then dominated, the 2000s-era of upscale television now practiced widely across the cable and streaming worlds.

Meanwhile, CNN Worldwide chief Jeff Zucker has been given charge of the sports units formerly in Levy’s portfolio, which includes Turner’s rights to National Basketball Association and Major League Baseball games.

And Warner Bros. chairman-CEO Kevin Tsujihara will be taking over Turner’s remaining content branch of Cartoon Network, Adult Swim, Boomerang and Turner Classic Movies.

Essentially, the company is splitting up Levy’s former responsibilities under Tsujihara (animation and TCM) Zucker (sports) and Greenblatt (TNT/TBS/truTV), the latter of whom also takes over for Plepler at HBO.

A more immediate impact, however, will be on the company’s personnel. Layoffs are expected as part of the reorganization in the coming weeks and months. AT&T paid more than $100 billion for Time Warner, and it is expected to be seeking cost-cutting measures as it looks to service the debt from that and other transactions.

AT&T reached its deal to buy Time Warner in late 2016, betting the latter’s technology and distribution infrastructure would fit well with, and benefit from, a vast trove of content assets.

Monday’s news marks the end of an era for HBO and TNT-TBS, which ever since the creation of Time Warner in the 1990s have been run separately, free to forge their own identities. The two have done just that, with HBO becoming an Emmy and subscriber powerhouse and Turner’s original programming on basic cable taking on a broader but still pedigreed feel.

What effect the moves have on both their content remains to be seen. Some fear in particular that HBO could lose some of the distinctiveness that has characterized the network since it launched “The Sopranos” two decades ago and continues with “Game of Thrones” and “Veep” today.

Greenblatt’s sensibilities run between the prestige and the mainstream.

As entertainment president at Showtime, he was responsible for shows like “Dexter” and “Weeds,” and as a producer he was behind the critically acclaimed “Six Feet Under.” At NBC, he put a more commercial spin on those tastes, with praised dramas such as “This Is Us” but also populist nonscripted fare like “The Voice.”

Greenblatt made his name as a young executive at Fox, where he once ran prime-time programming and unearthed a number of hits for a network that badly needed them. Among them was the teen drama “Beverly Hills, 90210,” a show whose generational popularity was on display Monday as fans mourned the death of Luke Perry.

How much Greenblatt will seek to change HBO remains a question. Given his pedigree, an expansion, not a reinvention, is projected by some observers. But others note that if quantity is important to AT&T — executives have been on record saying they want to up their volume to keep up with Netflix — it’s also conceivable Greenblatt would channel some of his commercial instincts into a rejiggered HBO.

Greenblatt noted in a statement that “WarnerMedia is home to some of the world’s most innovative, creative and successful brands and we’re in a unique position to foster even deeper connections with consumers.”

Also critical to this question will be whether much of the service’s programming leadership, including “Game of Thrones” overseer Casey Bloys, remains in place over the coming weeks.

The moves are part of a plan by telecom giant AT&T, which was cleared by the Justice Department to acquire Time Warner last year, to separate WarnerMedia content less by brands and instead form a general clearinghouse for video content. That strategy in turn comes in response to the rise of large direct-to-consumer competitors such as Netflix as well as Disney, which is making its own shifts in that direction.

There remains, however, a certain irony in WarnerMedia’s centralization moves as an anti-Netflix strategy. Though operating under one brand, Netflix in fact has something of a decentralized dynamic. Many of its shows are produced with outside partners, and creators operate with a large degree of freedom.

WarnerMedia CEO John Stankey noted that the change Monday “gives us the right management team to strategically position our leading portfolio of brands, world-class talent and rich library of intellectual property for future growth.”