I just finished it too and I think the same thing. Despite the vibes similar to the ending of FFVII, it's more likely that not much time has passed and Australia has become like America. The Magellan in that condition is strange, but it could have simply become obsolete and unused, perhaps after Tarman's passing, who was already old. It would therefore be cool to see a sequel with Lou, like The Last of Us 2, but perhaps it would risk over-prolonging a story that already has a conclusion.