The primary reason for his traveling to the past in the first place was to "right a wrong" (or however it's phrased in the game) where Olivia was killed, something that affected his mom (and his grandmother, actually) for the rest of her life... even when she ended up with Penny (another "wrong" that got "fixed"). It's always possible there's something more to make another trip to the past "necessary", but the primary reason(s) for going into the past have now been achieved. So some new "problem" would have to be introduced for that to happen. Again, definitely possible, but currently we have reason to think one is more likely than the other.