I'm currently on an AT&T Family Plan with two iPhone 3G phones and both unlimited data and minutes, but we've never really come close to even the monthly limits on the plans two levels down. (I've used 1.6GB of cellular network data since June 2009). I'd like to downgrade my minutes and data plans but I also want to get the new iPhone whenever it comes out. All of our lines are upgrade eligible. Would downgrading our Family Plan jeopardize our upgrade status?