I would like to read it, as long as there will be more than just the basic idea of "you can't be reliably better than the market, and the index funds copy the market".
For example, there are many index funds. I know they are supposed to be better than all other options, but how do I compare them against each other? Or, how much of the historical success of index funds is a survivor bias, that USA was simply not destroyed in a war, while many other countries were? (If you had invested your money in 1900 in Russian or German index funds, how much would you have today? Let's suppose you would put 1/3 in Russian, 1/3 in German, 1/3 in American index funds, how much would you have today? Is the advice for your readers to pick a random country, to always pick USA because that worked in the past, or to diversify internationally?)
I suggested recently that part of the problem with with LW was a lock of discussion posts which was caused by people not thinking of much to post about.
When I ask myself "what might be a good topic for a post?", my mind goes blank, but surely not everything that's worth saying that's related to rationality has been said.
So, is there something at the back of your mind which might be interesting? A topic which got some discussion in an open thread that could be worth pursuing?
If you've found anything which helps you generate useable ideas, please comment about it-- or possibly write a post on the subject.