In addition to a billion dollars or so in assets, Oprah Winfrey has built up major reserves of goodwill with her adoring audience.

All of which raises an interesting question for longterm Winfrey watchers — namely, is Oprah, like the major banks, too big to fail?

Even extraordinarily successful people can make poor career decisions, especially in regard to entertainment. In TV alone, a titan like Martha Stewart misfired on Hallmark Channel, while Katie Couric failed to replicate her dominant “Today” tenure on “The CBS Evening News.”

For all that, there are few talents whose track record is quite as jaw-dropping as Oprah’s. She’s testing her formidable brand on the Oprah Winfrey Network, a Discovery Communications co-venture limping through its infancy.

Before the May 25 signoff of her syndicated show (chosen to coincide with the end of the rating sweeps), the New York Times compared her final episode with Johnny Carson’s exit nearly 20 years earlier. Yet while Carson amplified his legendary status by walking away from “The Tonight Show” and never looking back, Winfrey is doing the opposite, asking fans to make a more significant commitment via her new platform.

So will the end of her syndicated powerhouse — a program that launched products and personalities like few others ever have — herald a bright future, or her diminution as a cultural and media force? Counting Oprah out would be silly, but given a choice, here’s a qualified bet on the latter.

To skeptics — or just those who find her program preachy in the extreme — that day can’t come soon enough. As easy as it is to admire Winfrey’s decision to rise above the daytime muck, there’s been something snake-oil-like about her “Live your best life” mantra, blunted only marginally by the host’s near-messianic fervor about using a normally passive medium like TV to make a positive difference in viewers’ lives.

Those eager to see OWN stumble are indulging in a bit of Schadenfreude. On the other hand, there’s something less unsavory about rooting against the famous and wealthy, if only because they possess more resources to cushion their fall.

OWN has already experienced several fits and starts, the latest being the decision to oust CEO Christina Norman after just two years in the job and four months on the air. That represented a reaction to low ratings, which haven’t much improved over predecessor Discovery Health, the channel whose programming OWN replaced.

Winfrey and her partners can designate whatever fall guys they like, but the truth is the network’s troubles largely stem from a major miscalculation: Launching OWN while Winfrey remained committed to winding down her syndicated program, and freely available to millions who’ve been watching her elsewhere. OWN thus possessed the Oprah seal of approval but not the lady herself, pushing surrogates like pal Gayle King on viewers, who have only so much time for self-improvement TV.

Ever since she steered away from tabloid topics, Winfrey has sounded like a New Age evangelist, and ample proselytizing for her philosophy was evident in her final syndicated episode.

The strongest impression watching that hour, though, was of a unique talent perfectly wedded to her venue, which she described as “exactly where I was supposed to be. … This is what I was called to do.”

It’s doubtful Oprah was similarly “called” to gamble her considerable capital on a dedicated cable network — one that went dark, in an act of respect and tribute, during her farewell telecast. Yet time will tell.

Winfrey spoke candidly in her closing about her belief in God, but she has expressed an equally unshakable faith in television. “Nothing can be compared to TV,” she told the Times, in its ability to form “an intimate connection.”

If OWN’s ratings get much more intimate, the channel could probably go dark permanently and few would notice. Should that happen, Oprah is a poor candidate for a bailout, but even fans might begin second-guessing what now seems quite possible — namely, that even after 25 years, she bailed out on her talkshow too soon.