The Internet is poised on the edge of a content explosion. For years now there has been a group of companies that grew up to help with Internet content delivery with products called (no surprises here either) content delivery networks.

So, with content ready to explode, the vendors already out there are in the catbird seat, right? Maybe not, because this might be one of those times when more means less.

The growth of the Internet has created numerous technical challenges. One in particular is how to make rich Web experiences work for millions of users without terabit core networks and server farms the size of metropolitan areas being required.

CDNs developed along with rich Web experiences as a way of providing a shortcut for delivering pages of content or media files from a cache server closer to the user. The user makes a content request by clicking on a link, and the request pulls the content from the nearest cache instead of dragging it out of the Web site’s data center and through a bunch of intermediary ISPs.

If CDNs are a good idea, it’s sure tempting to think that more content would make them a better one. If you look at CDNs’ value proposition, however, you can see some cracks. At the highest level, CDNs’ value lies in their ability to navigate the zone between so much content that caching is impossible and so little that caching is unnecessary. Surprisingly, the “more content for the Internet” trend is moving these extremes together and making that zone smaller.

Let’s suppose for a moment that the only IP content is television programming. In this scenario, every metropolitan area has its own IPTV server farm, because television programming is popular enough to justify serving it from separate major metropolitan area. Under these conditions, the servers that CDNs are short-circuiting are in the same places the CDN caches are, so there’s no value. The network connecting the user to the CDN is the same one — broadband access and the metropolitan network — that connects the user to the IPTV servers. No bypass there either.

Now let’s suppose that, instead of there being no IPTV, the YouTubes of the world own all the content and that millions or billions of users are uploading and downloading it happily hour by hour. What do CDNs cache? All the content in YouTube? Apart from the obvious storage challenge of keeping copies of the entire YouTube inventory in every cache, there’s the problem of how it can be updated there.