Im gonna change my theory about hank taking the family and kids because of what he said to walt when he found out about cancer. I think walt used saul's "last resort" option.
In either the episode where mike starts sobering jesse up or the one before it. Walt goes to saul's and vents about gus, mike and how he really is powerless. Saul then tells him about a last resort option where he and his family will just disappear.
Hence in the flashfoward he has a different identity, car etc..... Also explains why he didn't show the waitress his I.D. when he told her it was his bday to get that free meal