You can run, but you can’t hide. Facebook’s biggest user interface overhaul since the Wall, the Facebook Timeline, is now becoming mandatory for all users. According to the company, over the next few weeks, everyone will get the new Timeline. And here’s the important part: when you do, you’ll have just seven days to preview what’s there now, and hide anything you don’t want others to see. [Update: Facebook did not immediately require migration for those whose shrugged off prompts to switch, but plans to push forcibly push Timeline to all users by Fall 2012]