I can appreciate the concerns over scaleability with this one. Here's where I really get going. My core philosophy in this debate is that we must build paved roads where paths are already beaten down. In other words, follow the lines of growth rather than fighting them. There need not be any more of these than there are TLDs.
Purpose is to simplify domain research.
What I am describing here is not an open fulltext search engine, nor a structured hierarchy index like Yahoo. Most domain registrations require a brief paragraph outlining the purpose of the domain. Let us create a TLD just for search engines. It's not just the big guys any more. There are thousands of regional and local and topical search engines all over the Net.