This may be the last time I ever write about Tina Brown.

Brown once dominated the New York media world. Even as she lost influence, she tenaciously held on to a series of always much-talked-about positions in it, and was lovingly, cattily covered by several generations of media reporters. Now, she has lost her most recent and, likely, last perch: as founder, editor and impresario of the Daily Beast.

Brown deserves a valedictory. She arrived in New York from London before she was 30 – with her eminent husband, former Sunday Times editor Harry Evans, then 57 – salvaged the relaunch of Vanity Fair and became the crush of every male writer in the English speaking world. Her procession then took to the editorship of the New Yorker. Controversially modernizing what was regarded an American cultural institution, Brown significantly advanced the ever-blurring line between the literary and the commercial. And then, in a bid for the new wealth that she helped mythologize, started her own venture, with the backing of Harvey Weinstein, Talk, a magazine, and movie company, and book publisher. It shortly failed.

There followed television presenting jobs; a wilderness period in which she hosted promotional parties for a fee in her home; the publication of quite a good book about her doppelganger, the Princess of Wales; and finally, the Beast – oh, and then Newsweek, too.

The Daily Beast was an effort not just to restore her stature and income, but to catch her rival Arianna Huffington, who was suddenly achieving prominence and wealth in the new world of blogging and online journalism. Brown, famous for gulling rich men, convinced the otherwise savvy mogul, Barry Diller, whose company IAC managed a stable of digital properties, to support her in this enterprise.

Brown was Diller's experiment, but Brown – ever an empire builder – may have taken it all much more seriously than he had intended. She shortly recreated, in IAC's Frank Gehry building on the Hudson, an ever-expanding publishing operation in the old style. In a digital world of strained circumstances, she hired editors, paid writers, killed pieces, rethought and revamped and redesigned … and generally conducted herself as much as she possibly could as though the world was still recognizable, even comfortable.

As the Beast faltered, or failed to grow at the pace of its competitors despite spending more, Diller took a leap of desperation or wild imagination: he hooked the Beast up with an after-death rebirth of Newsweek. The pain and hopelessness of this effort was public and mortifying, for all concerned. Diller, a man not much accustomed to such admissions, famously regretted his "mistake".

Brown's last exit, at the age of 60, is not a surprise – except for the fact that she has so often pulled rabbits out of the hat that one should always qualify the writing on the wall about her.

The cover story about her future is that she is taking with her the money-losing women's conference, which the Beast sponsored. This, it is said, will be the focus of her professional efforts, along with a new company reportedly being called Tina Brown Live Media. Perhaps.

It is certainly true that in her 30 years in New York, she has built an asset base of celebrities. Her present predicament, though, ought to give a good indication of what celebrities are worth when you are only of ever-more limited use to them. She is, in a sense, now wholly dependent on their kindness.

Curiously, her apparent age disadvantage – an inability to grasp the customs of the digital era's more leveled world – could still work for her. Although she herself has amassed nothing much to speak of, she yet moves among the last media generation of power and wealth, including many who yet want to congratulate themselves.

Brown has never been good at astutely analyzing the market, or disciplining her inclinations to the constraints of the opportunities at hand. But there could be a business plan here – making older celebrities feel that the world is still theirs.

But I am being catty, reflexively so. Once no one dared write anything negative, but it has been a long time since anyone wrote anything positive about Tina Brown. Yet, she is simply a representative figure of the struggles of modern media life, rather than the person who should be blamed for it.

Magazines – knowing, insidery, cruel, fawning, beautiful, upscale (remember that word?) magazines – died, leaving her without a profession. The rich and clever who were the subjects of her magazines became strangely equivocal figures. New York itself moved to Brooklyn. And then, without warning, she had to learn the methods and sensibility of the new digital publishing world, which must have seemed like another country to her.

It is a sad story, which, in spite of its often comical excesses, is hard not to relate to.