Well, from what I remember, LW has always been diverse. There is a core that has been interested in AI risk since EY's early writing and the SL4 mailing list. There is a newer group that HMPOR brought in, and so on. Some of these groups explicitly complained about too many posts in categories they were not interested in.

One of the proposed solutions was to fork LW into subreddits. That's what reddit does after all, and it seems to works for them.

What happened instead was the exodus - a fork into separate sites. The EA people have their own forum now. The rationality bloggers hang out on blogs/facebook. The MIRI AI risk people have their own forum as well.

My worry is about the lack of centrality,

How does centrality in particular help? I mean it helps a little to have less pages to load to get the content that you want, but on the other hand when posts are too frequent its annoying to have to wade through a bunch of stuff you are not interested in. LW of course is now pretty low volume - but if you look back at the history, there was a time when people were complaining (numerous people at various times) that there was too much stuff they didn't like (at least this is how I remember it, but I'm not even bothering to search to find some example posts).

strategists and thinkers can start to be seen and dinosaurs can come to post their new ideas

I just saw Jurassic World - so my mind is having some extra trouble interpreting your use of 'dinosaurs'. I guess you mean old high quality posters who no longer post?

If you have some ideas you want to write and communicate and get feedback on, then your best bet is probably to write them up first on your own blog, and then submit them for discussion on multiple sites, and then gently link the resulting discussions together. Also, directly emailing people and asking for comment is sometimes useful - totally depends on your goals.

The other strategy is to just write stuff and let the internet figure it out. I dont blog so much recently, but when I used to blog more I just wrote articles and never bothered with promoting them or even telling anybody about them in anyway (not even my friends). Surprisingly, people somehow found some of the better articles regardless, and this even lead to some very interesting discussions - basically I met John Smart that way. I even made a little money when one of my articles was turned into a column on game developer magazine.

So anyway - it's not clear to me that centralization helps enormously. It has some advantages, but also some serious disadvantages. For example LW is open, but that does not mean that it is completely free of top-down influence from MIRI/EY - which some writers of very different viewpoint would find annoying/unacceptable.