Actually this is the tour. The leader after today will not be passed. That is the tradition of the event. Sunday is a party and for show only. No racing on Sunday.
My Dad was telling me today that the year Greg Lemond won he was behind by something like a minute going into the final stage - so if it tightens up a little bit after the time trial you never know.
Not true -- the Green Jersey is up for grabs and usually it's decided by the sprint at the end.