If each "major" club were to get it's own thread, then I would be completely and utterly against this as I believe it would ruin the atmosphere of CSE and create such a huge amount of clutter that it will destroy the community. Let me explain:
With 30-40 threads on major clubs together with more general ones, and saying that there are 20 or so used quite actively, yes it would bring activity to this forum, but it would so something else. It would stop new challenges, new AI experiments, and new sign-ups from getting the exposure they need, near the top of the forum, to grab users attention and get people to look at them.
The beauty of CSE is that threads can get attention from users when it hasn't been posted in a week. An AI Experiment, and I mean a meaningful detailed one, cannot be updated continuously, and is normally updated by one person alone. Now people will follow it, but they won't post in it that often and nor will updates come that often. It will however, under the proposed changes, quickly sink down the forum and gather little attention.
The same can be said for new challenges, of course the established challenges like Dafuge's and Gundo's will be perfectly fine due to the volume of users, but other challenges which need to be near the top to get attention and users will be relegated down the list of threads rather quickly and be cluttered up with "Man Utd Career Games", "Liverpool Career Games", "Real Madrid career games discussion".
The beauty of this forum is watching a sign up, an experiment, or a challenge which is quite small build up a following over time, build up discussion, and build up interest. This will be lost if there are dozens of non related threads.