NEW YORK (FORTUNE) - All Web sites are alike. Regardless of their owners, they can all do the same set of things. In that fact lies the profound crisis facing all aspects of the media industry.

It doesn't matter whether a Web site's owner once focused on publishing newspapers or magazines, broadcasting television or radio, making music or producing movies, or even selling soft drinks. Any Web site can host text, audio and video, it can facilitate connections and communication between users, and it can enable those users to create and display their own text, audio or video.

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Coke (Research) can release music; ABC can publish articles; and Forbes or The New York Times can broadcast video.

The Web is one big level playing field of competition for the customer's time and attention. The quality and relevance of the content will be what drives viewers to devote that attention - not whether the host happens to be Coke.com, NYT.com or Disney.com.

So should a magazine like Time, Rolling Stone or Fortune still think of itself as in the magazine business if a growing portion of its readers are seeing the content it produces online? Or should it produce content of all types under its brand there? This kind of existential question burdens - or should burden - anyone who creates or distributes branded information or entertainment.

How should a sports fan decide, for instance, whether to go for his or her news fix to ESPN.com or SI.com? Most likely the decision will not have much to do with the fact that one organization was historically a TV network and the other a magazine. The sports fan seeks good sports content - which can now be distributed in all forms online. And indeed, SI.com has scored a hit with regular video segments on its Web site from columnist Rick Reilly.

But this new media egalitarianism strikes an even deeper blow against conventional thinking - and existing business models. While it hasn't much happened yet, what if big consumer brands decide to take their audiences and become media brands as well? If Coke, for example, could in effect operate its own TV station online, would it still buy hundreds of millions of dollars worth of ads in other media?

Or take a company like Clear Channel (Research). We are rapidly moving into an era in which you can get your streaming or downloadable audio content (whose predecessor forms we quaintly called "radio") from any site, be it MTV.com. Walmart.com, Fortune.com, or DavidKirkpatrick.com (which, sad to say, I do not own). This becomes more true as Internet access gets more ubiquitous and moves onto mobile devices like those in our cars.

I don't believe this inevitably means the demise of all old media. But it does require a conscious, open-minded, and sometimes painful re-evaluation of what business we are all in. I suspect that the successful magazines of the future, for instance, will be those thoughtfully tied to a much richer online experience. Ditto with TV stations, which will need to offer more than plain-vanilla broadcast.

The new Web site egalitarianism may then lead to a wholesale restructuring of media around brands that exist in multiple media. ESPN is probably a bellwether here. Its brand now applies to successful TV networks, a magazine and a Web site. ESPN stands for quality sports content, regardless of the platform.

Of course, content cannot fungibly migrate between mediums. Certain kinds of content are best suited to print - like thoughtful and detailed political analysis, or dissection of corporate strategies. Some kinds of video will work best on a big theater screen, others will be fine in a tiny Web site window. (The phenomenal recent success of YouTube suggests, though, that there is more of the latter than any prognosticator would have imagined.)

If there's any consolation in all this for giant old-media companies, it may lie in the fact that new net-only businesses are not generally figuring it out much better.

Today most of the dominant Web sites are only beginning themselves to take advantage of the rapidly-growing multimedia capabilities of the Web. Yahoo (Research), for instance, has its dollop of video and a good music site but remains mostly a textual experience, even though it's considered a paragon of new media excellence. Amazon (Research) and eBay (Research), too, barely include video. (On the other hand, eBay has taken a major step toward the unbounded future by starting to incorporate free phone calling from Skype into its retail experience.)

Another consolation for old-media hand-wringers: For now, advertising spending may still be streaming online, but ultimately it will be proportionately calibrated to the amount of time consumers spend in various media. And people will surely continue to use many different kinds of media. (Today, the percent of consumer time spent online still far exceeds the percent of ad dollars invested there.)

In the meantime, the day is approaching when your faithful "magazine" columnist speaks to you in moving pictures.