Good news guys, I have a friend who has been on hold for 11 years he just got his Welcome letter last week. I think the average pending application take around 10 years, well I have been on hold almost 6 years so I have 4 or 5 years to go lol.
I don't think that is how it works, if you go through previous threads some of 212 a 3 b on hold got their Green cards approved, and few of them filed in 2006 and in 2007.
I hope you take it as a good news.