Since there is the potential to make so very much money on the web, threats to a Known Space project come from many sources: search engine companies, browser manufactures, interface designers, hardware manufacturers, electronic news agencies and encyclopedias, and non-profit groups. Known Space's very inevitability tells against it since so many groups will likely be able to see its importance after just a few more steps of development of their various products.
The natural place for a Known Space project to start is at one of the search engine companies, particularly Excite, AltaVista, and Infoseek. Fortunately for Known Space, however, search engine companies apparently don't yet seem to realize that mapping is a lucrative service for someone to provide. Of course, this may be illusion and major search companies may be even now working on their own versions of Known Space.
The single most important first step toward the Known Space idea is to have recently visited pages stick around for a while when the current page is being downloaded. This lack of direct display of recent documents is what makes it so very easy to get lost in webspace. The next generation of browers from Netscape or Microsoft might make this a standard feature, thereby making Known Space less important. Further, as soon as they do it, they'll likely see its importance and keep expanding its capabilities, thereby creating their own version of Known Space.
Another important advantage of Known Space is the embedding of a knowledge base in a memorable, perceptible, and interactive space. Several companies like General Magic, Sun Microsystems, and Apple are making steps toward that ideal with their interfaces or searchers.
The third important advantage of Known Space is its semi-autonomous accumulation and testing of candidate sites. Such ideas are likely to occur to many people as the population base of users of distributed and secure languages like Java and Penguin increase. Known Space may be supplanted by freeware versions that make it less viable as a commercial product.
Various groups that publish heavily on the web might start sharing their views of data thereby making Known Space less relevant. All the universities in the world, perhaps starting with North America, could conceivably create maps of departments, faculty, students, and subjects at all of their sites. All the libraries in the world could do the same, as could all the news agencies, and so on. Such pooling seems less likely for many commercial sites however. But there might be strong advantages for many if they can get over their competitive instincts--for example, all the world's realtors, all the world's travel agencies, all the world's sports equipment manufacturers, and so on.
Finally, someone is likely to create something like Known Space as soon as many users' bookmarks file contains more than a thousand or so sites. How will they keep track of that many bookmarks without some kind of mapping of what's there? It seems likely that more and more users will save key information somewhere in the webhome then forget where. Clustering the bookmarks file into neighborhoods (which is one of the side-effects of Known Space) is better than having to click on every site in the bookmarks file to re-find such ``lost'' information. Further, what happens if the web's transience increases so that even if the user clicks on the right site the site is no longer there, or has been modified? Known Space puts some automation between the user and the searching task and that, however it is to be realized, seems inevitable.