Who do you want to access your post?

So this posting to "friends and family" only thing is nice, but realistically - how private is anything you post on another persons server?  In some future scenario ten years down the road when Six Apart is just the collective memories of a bunch of striped-shirts and all that remains of Vox is a cobwebby database of posts owned by some bank or data vulture, whose to say that my long post about how my favorite album cover is the one I snorted my first rail of ketamine off of doesn't end up directly associated with my credit report or NSA file?  Unless maybe it involves medical records, a "privacy policy" probably doesn't amount to much

I guess this is one of those info age questions that everyone asks at some point when they find themselves on the razors edge of converting some questionable part of their personal life into online social currency by blogging it.  But I wonder if I'm being a tad paranoid to think it appropriate to just assume that all that which seems semi-private now will one day be indexed on the google of the future?