Paramount and Skydance said on Sunday they had reached an agreement to merge, a deal that would usher in a new era for CBS, Nickelodeon and the film studio behind the “Top Gun” and “Mission: Impossible” franchises.

The deal is a turning point for the Redstone family, whose fortunes have been intertwined with the rise and fall of the traditional entertainment industry during the decades of its tumultuous ownership of Paramount and its predecessors. Shari Redstone, Paramount’s board chair, is cashing in much of her ownership in the company she fought to preserve and control.

The merger has a “go shop” period that will give Paramount’s board a 45-day window to see if it can find a superior deal.

But if the Skydance deal closes, it will anoint a new mogul in Hollywood. David Ellison, the tech scion behind Skydance, will become the top power broker at Paramount. The deal is in some ways the story of media writ large, with a family that made its fortune in traditional entertainment largely replaced by one enriched by technology — Mr. Ellison is the son of the Oracle founder Larry Ellison. The Ellisons’ considerable resources were a major selling point for the Redstones, who were seeking to shore up Paramount for the long-term.

“Given the changes in the industry, we want to fortify Paramount for the future while ensuring that content remains king,” Ms. Redstone said in a statement.

The merger closes a chapter for Ms. Redstone, 70, who took over from her father, Sumner, and fought to keep the family media empire intact.