NEW YORK (AP) — Jay Leno and the "Tonight" show is one of the few remaining successful programs that NBC has on its network. So why would its executives think about getting rid of him?

NBC has confirmed that it is building a new studio for Jimmy Fallon at its New York headquarters but refuses to comment on reports that Fallon is due to replace Leno on a New York-based "Tonight" show as early as next year.

With Leno already taking potshots at network executives regularly in his monologue, the network risks repeating the nightmare of 2010, when Conan O'Brien failed at "Tonight" and NBC brought Leno back.

"They seem to be making the same mistakes over and over again with a new regime," said Christine Becker, an associate professor at Notre Dame University and author of the News For TV Majors blog. "You kind of wonder what's in the water at NBC that is making them make that decision."

On its face, such a move would seem like a proactive strategy from NBC's new corporate owners at Comcast Corp., known for its decisive decision-making.

Leno, 62, and his longtime rival David Letterman, 65, are approaching the end of their long late-night reigns. Fallon, 38 and with his own late-night show getting critical acclaim, represents the next generation. So does Jimmy Kimmel, 45, at ABC, and that network made the strategic chess move in January to give him the same time slot as Leno and Letterman.

Leno's contract expires next year and so does Letterman's, so some corporate fear might be involved: Does NBC risk losing Fallon to another network that can offer an earlier time slot than the 12:35 a.m. one he currently occupies? There's also some concern that Kimmel will establish himself as the 11:35 p.m. favorite of a younger audience before Fallon can establish himself.

While all the corporate thinking is going on, Leno has continued to stay in the ratings lead.

That's no small feat at NBC, which has seen its prime-time lineup collapse to historic ratings lows this winter. Leno, "Saturday Night Live," and Brian Williams' "Nightly News" are the only reliable ratings leaders left at the network.

Leno has held strong against the ratings challenge posed by Kimmel. So far this year, the "Tonight" show is averaging 3.42 million viewers, Letterman has 3.03 million and Kimmel has 2.57 million, according to the Nielsen Co. Leno is also leading among the 18-to-49-year-old age group that NBC considers most important. Leno's and Letterman's viewership has gone down from last year; Kimmel's numbers aren't comparable because he now has an earlier time slot.

If NBC is looking for an immediate infusion of youthful energy from Fallon's audience, that may be optimistic.

While the average age of Leno's audience is 58.1, the oldest in late-night, Fallon's audience is less than five years younger at 53.3. Fallon also hasn't been gaining in popularity; his average audience has slipped from 1.7 million last year to 1.6 million the year before, according to Nielsen.

Younger audiences seem to be elsewhere at that hour, either online or watching cable. The median age of O'Brien's audience is 39.5 and Chelsea Handler's is 35.6. Both Jon Stewart and Stephen Colbert have audiences with median ages of 42.

When O'Brien replaced Leno at "Tonight," the audience didn't follow. The "Tonight" show ratings dipped alarmingly, and NBC had to bring back Leno to stave off a revolt from its affiliates. There's no guarantee that Fallon will succeed where O'Brien failed.

There's also the specter of Ann Curry, which should be fresh in the minds of NBC's new corporate ownership.

When NBC News replaced Curry as co-host of the "Today" show last summer, viewers reacted angrily — fixing much of their anger at Matt Lauer. "Today" was running neck-and-neck with ABC's "Good Morning America" in the ratings at the time; now it regularly finishes second.

How Leno's fans would react to the idea of him leaving the "Tonight" show before he wants is anybody's guess. Leno, with a relentless run of jokes targeting the futility of NBC executives in recent weeks, doesn't seem particularly happy.