Given the fact that you already have done the story from two separate points of view, if you were to make a new installment to expand upon this world, there is a potential of multiple routes that could loop around into each other. Go with Dog, stay and help Dog, then go Cat, then home. Go with Dog, leave Dog for Cat, then home. Go Cat, then go Dog, then Home. Go Cat, Go Home. Each choice would impact the intensity or rate of progression, for better or worse, of events. By the end, assuming all 4 paths chosen, there would be a good deal of more to the world you have made here and it would only set he groundwork for even more. It would have come full circle enough by then that a third installment may not need to have any of these characters as the main cast, but still acknowledge they exist. These ideas are not a must, but this seems to be the potential they have.