Alive. Both of them.
But, IF they are indeed coming back, then there needs to be some big changes.
1. Clearly and effectively differentiate Jonathan and Martha as two very different people in the opposite attract mold, and show how Clark is the best of both their personas. Maybe Martha is more a "Are you doing enough?" type with Clark while Jonathan is more a "Are you doing too much?" type with him.
2. Let them bicker and argue amongst themselves and with Clark. Older parents and their adult children tend to have more complicated (but still healthy) relationships. Clark can and should think that he's right and they're wrong at least some of the time.
3. Give Martha a job. Jonathan is a farmer-turned- military-turned-back-to-farmer. Martha needs a career. I propose rural pediatrician.
4. Let Pete Ross be the sacrificial lamb who dies young from undiagnosed cancer or something (no foul play) and young Clark is powerless to stop it, and thus learns he can't do everything. "All those powers ... and I couldn't even save him" must survive, even if the subject of that all- time poignant quote changes.