The game is dying, despite the drop in people online at a time. There's still over 600 people that log on a day, so I don't really think that's qualified as 'dying'. There is school, as others have mentioned, that hold people back from getting on the game so the maps are going to look empty for a few hours, but eventually they do fill up, and are as lively as ever.
Welcome back, though! I hope you decide to stick around with us again because we'd love to have you back.