Coming soon to a television near you... the new US blockbusters

On Sunday, we will lose Lost. A day later, time will finally run out on Jack Bauer's 24. They will join the once-modish Heroes on a scrapheap of recently axed television shows which has grown so rapidly in recent months, that Hollywood's trade press has begun wondering if hatchet-wielding TV executives are falling victim to a highly contagious disease known as "prime-time panic".

It only feels like yesterday, after all, that ER, which had run for 15 years and inflicted George Clooney on the unsuspecting world, was finally canned. And last week, Law & Order, America's longest-running TV drama, was dropped, ending two decades and more than 450 episodes of faithful service. Not since 2004, when Sex and the City, Frasier and Friends simultaneously ended, have so many era-defining programmes disappeared in one big swoop.

A billion-dollar question is therefore now floating over future viewing habits of not just America, but the roughly 130 countries where its television is syndicated. What new shows, in the endless array now being commissioned to fill newly vacant airspace, will become the game-changing hits of tomorrow? Or to put it another way, will any franchise, in an increasingly fractured creative landscape, turn into this decade's 24, or Friends, or Lost?

The TV industry's biggest cheeses are currently meeting in New York to find out. All week, major networks have been taking turns to host networking events, cocktail parties, and star-studded presentations at which they brief agents, journalists, and advertising industry "buyers" about the collection of new programmes launching this autumn. In keeping with its forward-thinking remit, the annual event is called The Upfronts.

This year, an unusually high total of roughly 30 new shows have been showcased by the "big four" networks, NBC, ABC, CBS and Fox. In large, expensively decorated theatres they have screened endless trailers and highlight reels, hiring major talent to help pitch their new wares. Fox's Upfront, on Monday, featured a song and dance performance from the cast of Glee. NBC's was presented, like the Oscars, by Alec Baldwin.

Financially, the stakes are huge. Scripted drama costs upwards of $2m per hour to produce, so each new series sets its broadcaster back tens of millions. Yet the vast majority end up as costly flops: only about one in ten will survive beyond a second series. Even fewer reach 100 episodes, the point at which they become major cash cows, making household names of their cast and creators, and earning billions for the lucky network in DVD box sets, and worldwide syndication rights.

Predicting what will end up in the hallowed circle of winners is never an exact science. But if there was an award for the new show enjoying the most hype, it would go to Steven Spielberg's Terra Nova. This project, due to launch in early 2011, comes from the Jurassic Park school of film-making: it centres on a modern-era family who travel several million years back in time to the era of the dinosaurs in order to save the Earth from environmental catastrophe.

Fox has appointed two of the newly unemployed producers of 24 to run Terra Nova. It has not yet been cast, meaning that audiences at this week's Upfront were unable to see preview clips (and instead were simply shown conceptual art). But with its state-of-the art special effects, an enormous budget, and tree-hugging themes, it ticks similar creative boxes to Avatar, the most lucrative film of all time.

Alongside Spielberg, another big-name producer returning to the fold is JJ Abrams, the creator of Lost, who in recent years has been responsible for a string of intelligent science-fiction shows like Alias and Fringe, which achieved cult status on both sides of the Atlantic. His new show will be called Undercovers, and is about married ex-CIA agents who are running a restaurant, but decide to come out of retirement when a close friend suddenly disappears.

Abrams has cast the British actress Gugu Mbatha-Raw, who played Jenny in Spooks and was recently Ophelia to Jude Law's West End Hamlet, in one of his two lead roles. Her co-star is Boris Kodjo. Their appointments represent a gamble: series with mixed-race protagonists are often successful in the US and UK, but (for entirely regrettable reasons) can be a tough sell in some foreign markets.

The final household name getting in on the action is Jerry Bruckheimer. He has a new legal drama called The Whole Truth, which uses a split narrative to show how both sides in a court battle construct their case. Its pilot was excellent. But that episode's success may be hard to replicate: the show's British star Joely Richardson, has suddenly quit the cast for so-far-unexplained "personal reasons".

Bruckheimer, who is never afraid to explore well-worn genres that involve lots of car crashes and special effects, is also behind a second new show: a cop drama for NBC called Chase. It's described by the network as "a fast-paced drama that drops viewers smack into the middle of a game of cat-and-mouse as a team of US marshals hunts down America's most dangerous fugitives".

Neither he, nor Spielberg, nor Abrams is exactly renowned for budgetary restraint: Fringe had the most costly pilot in history, while Spielberg's recent HBO series The Pacific, which cost $200m for ten episodes, is the most expensive TV series ever made. Their success in getting the green light for major shows suggests the industry may at last be emerging from its recession-era financial torpor.

"The advertising market has finally started to pick up, along with the rest of the economy, so there's an air of optimism here. As revenue grows, so does confidence," says Nellie Andreeva, who is covering The Upfronts for the influential Deadline Hollywood Daily blog. "Advertisers will pay more for slots in quality scripted drama shows than in other, cheaper kinds of programmes, so that is one reason why so many are being launched."

Among the other new programmes she's seen showcased this week, Andreeva also rates two ABC projects: No Ordinary Family – a "family version of Heroes," in which a mysterious plane crash leaves a family with superpowers – and My Generation, a light-hearted programme about former schoolmates shot in a "mocumentary" format.

CBS is touting a Criminal Minds spin-off starring Forrest Whitaker, along with a show called Blue Bloods featuring Tom Selleck, and a rebooted Hawaii-Five-O. A new soap opera from Fox called Lonestar, starring Jon Voight as a Texan oil baron, will pitch for the market once owned by Dallas.

Other new launches generating buzz are the comedy Outsourced – think The Office, but in a Mumbai call centre – and Mr Sunshine, in which former Friends star Matthew Perry plays a forty-something man coping with a midlife crisis. British viewers will get to see the best of them next spring, when they get picked up by UK broadcasters.