I think the problems are;
Facebook has taken away a lot of posting from ALL forums
A lot of people have moved on in their lives and settled down/less time due to work etc
We're all that bit older as well and maybe don't listen to old skool stuff as much as we did a few years ago, I really dig Jazz Fm these days with their late night downtempo lounge slot and the funk stuff they play during the day
Loads of other sites have sprung up trying to be like OSA but failing badly and just a few cliquey people joining and posting on them all - pretty pointless really but people have to try an imitate and it is a form of flattery after all
The solutions ?
Integrate OSA with Facebook so that posts can be liked/tagged easily and encourage more interaction as this is the way forward nowadays and the more that talk about it are likely to listen/pass on the link which would pull in more listeners.
What about having scheduled styled days, examples
Monday - Hip Hop/Electro/Soul/Funk
Tuesday - Techno/Acid/New Beat
Wednesday - Deep House/Garage
Thursday - Dubby House/Progressive
Friday - Anthems/Breakbeats/Jungle etc
Saturday - Anthems/80's guilty pleasures
Sunday - Chill Out/Downtempo/Lounge/New tracks allowed
You'd then have an idea of what to expect on a certain day, like a proper radio station (think Sunset 102)
It would also break up the same old same old that we suffer from and I think could pull in different crowds and have more people chatting/posting on the forums about the different styles of tunes played, especially hip hop/electro and the downtempo stuff that doesn't get enough air time.
I'll return with some random sets in 2012, won't be the usual stuff though - something completely different