[Spoilers] Epilogue - Could humanity be restored? Updated 12-27-2016

[cantremember]

I don't think the Ark could return to earth, it probably has no means of safe re-entry and landing through the atmosphere. Even in space the life isn't limitless but described by Cath as "thousands of years".

Whether a corpse/robot running a formerly human's brainscan consists as a "human" is pretty much the question that the game wants the player to ask himself. In my opinion such creature is a life worth protecting, but the surface being populated by such beings is IMO not good enough to call it a "restoring humanity".
Also I think Simon needs energy to run. Cath's conciousness is suspended whenever she isn't plugged in, and I think Simon relies on battery power (and WAU flower charges) to keep his cortex unit and structure gel from failing. Many other robotic creatures also quickly die when they are unplugged from the WAU.
Even if the robots could go onto dry land, I don't think they have any reason to, there is nothing there for them, Pathos II is the only place left for scavenging and energy.
They also only have so many brainscans, they can't naturally replicate or create more "humans". They might be able to extend humanity's legacy, but at the risk of creating more suffering (like the WAU did)

I don't remember what Pathos I (or if there was a Pathos III) was, but my impression was that the facility was a unique thing in the world. The other Pathos locations were on the surface. The last human in the infirmary also believes she's the last human on earth. I suppose it's possible that another nation had constructed a secret underground base somewhere that the Pathos staff were not aware of, that would be very cool in my opinion for a sequel.

My idea is that humanity is toast, and the only thing left in the world is marine life. The WAU infected ones won't get far but there are also plenty of unaffected sea creatures still living in the ocean.
Main reason for me is that Simon really being abandoned to his fate in a dead world makes for a much more powerful ending.

The only real chance they had was if the WAU didn't go coo coo and the crew gained the ability to catch marine life for food. Perhaps they could have lived in Pathos II long enough to leave back to the surface before the station wears/breaks down due to erosion, as they also aren't getting new supplies to maintain the facility.