As I am getting closer to finishing my third volume, I already have the fourth and fifth volumes planned out.  The fourth volume will involve an alien invasion, but these aliens will be formidable and will be difficult for the Young Guardians to defeat with their present numbers.  With that in mind, the fourth volume will also involve the Young Guardians recruiting more members for their ever-growing organization to combat future threats to humanity.  As for the fifth volume, it will include the Young Guardians battling the main villain of the entire series one last time and Armageddon will be unleashed upon the world as they do so.  I will keep you posted on any further developments.  Wish me luck!