Lance Armstrong's Livestrong in Jeopardy?

Ask any marketing guru, and they will tell you: Lance Armstrong probably earned his final legitimate sponsorship dollar.

Lance Armstrong's Livestrong in Jeopardy?

"Barring him proving his innocence, he is completely done as an endorser," said Bob Williams, CEO of Burns Entertainment & Sports Marketing, which matches celebrities with advertisers.

Once Nike read the U.S. Anti-Doping Agency evidence of Armstrong's alleged doping, it decided to drop him.

Within hours, almost all the other companies attached to Armstrong followed suit. (Read More: Armstrong Loses Eight Sponsors in a Day.)

In the mass media, many compared Lance to Tiger Woods. Why would Nike stand by Woods, who admitted to infidelity, and not stand by Armstrong?

Easy.

Tiger's behavior was personal. Armstrong's was professional.

"Lance Armstrong hurt sports, not like Tiger who hurt himself," said Sam Poeser, Nike analyst for Sterne Agee. Poeser added that Livestrong products produced no more than $100 million for the $20 billion company.

Now, the issue isn't Armstrong.

It's the Livestrong brand and foundation. (Read More: Lance Armstrong Resigns From Charity.)

Armstrong founded it for cancer research, and the symbolic yellow bracelets were a national sensation. Livestrong has raised about half a billion dollars, and more than $33 million this year alone.

Almost all the companies that dropped Lance as an endorser went out of their way to reiterate support for the foundation — and the cause.

However, CNBC talked to several brand experts who said that kind of support is a marketing no-brainer. It says nothing about the LONG-TERM support of the foundation.

"I don't think, long term, it will be able to survive," said Williams, who has been matching companies with celebrities for almost 20 years.

"Livestrong is living on borrowed time and is on life support."

That is strong language.

But consider this: Lance Armstrong will always be a cancer survivor. But Armstrong's entire success story is the core — perhaps, the soul of the foundation. (Read More: Armstrong Leaves Livestrong on a Rocky Road.)

That story has been destroyed.

"He's put himself in the worst possible position by the way he has defended himself over the years," Williams said.

—By CNBC's Brian Shactman
@bshactman

Shactman's Sport Stocks:

-Nike

-Under Armour

-The Madison Square Garden Co.

-Manchester United

-Dick's Sporting Goods

-Foot Locker

-Callaway Golf

-Hibbett Sports

-Adidas

-Finish Line