It is highly unlikely that a series like LOST would today be made on a traditional network.
It seems all the unconventional shows are being made on HBO, Showtime, SyFy or BBC America.
The fracturing of the Nielsen rating viewer is also a factor in why large ensemble cast shows with long serial plot lines have fallen out of favor. They are just too hard for casual viewers to follow.If you can't follow, they will not watch.
Cable television could get away with running a full episodic season for a television show because there was not the advertising fever in the executive suites. Cable networks made their initial money from just being on cable operators menus with carriage fees. But as the cable network has matured and the viewership fractured from the Big Four over-the-air networks, advertising has become more of an issue for every type of broadcaster.
In addition, new forms of distribution have started to make a run even at cable broadcasters. Netflix and Amazon are using streaming technology to run their own new programming to viewers. YouTube had been running advertising on its "channels" for years under a model of mostly free, user created content.
The new streaming shows fit into old network shoes like one camera situational comedies rather than grand, on location ensemble dramas like LOST. And the new medium has not been able to have the support to keep a show running for six years.
In all broadcast entertainment, shows are hits and misses. Every year the networks have a "pilot" season where hundreds of test shows are reviewed to determine whether they will be picked up. Out of that production company pitches, only a hand full will get the green light. It is a long shot to get anything substantial made today, even though there are more outlets of show distribution.
The economics of the entertainment industry is growing, but at the same time narrowing because viewers can cut the cable cord and be entertained in various alternative ways. The newer game consoles have tried to recapture some of those lost demographics by integrating TV and streaming multitasking to create a "new" TV experience.
If the show runners came to a network today to pitch LOST as a Survivor meets Agatha Christie meets Star Trek, a network executive would reply that they already have those shows; do you something else to pitch?