It's possible that they still live while Mike is asleep? Using that idea, I think another game could be possible.
I like Manere's idea, but there is a small problem with it. It supports the theory that the raposa are just a dream... What if Mike AND Heather dream about the raposa? And as they get older, they share the raposa with the outside world.
I personally think that they were never alive. As we know by the ending of Dawn To Life: The Next Chapter Mike was in a coma the whole time when we played though both of the games. And after we defeated Wilfre for good is when Mike woke up, as the screen turned to white. And since the Raposa where never alive, just a image of the two prizes of what Mike and Heather won at the carnival, they will probably only live in Mike's imagination