According to this Metrolink website news story, things will be back to normal (or as normal as they can be after recent events) as of tomorrow:
Beginning Monday morning, Jan. 31, Metrolink trains will begin operating on their regular schedules on the Ventura County and Antelope Valley Lines. We would like to thank you for your continued patronage and support during these difficult times. Thank you for riding Metrolink.
On the front page, the site mentions that one of their own employees, Conductor Tom Ormiston, perished in the crash. His funeral is 11:30 tomorrow morning at Forest Lawn. (Details here regarding donations and cards.) nbc4.tv has a list of the other folks who were lost, lives cut short in this senseless tragedy.