I think this idea might help make CIU a modern game. You might say, “Oh, this is just a reference to that one unlockable from CI5” and you may be correct. However, the design and such tiny details such the egg would make a fine addition.
After three years, it is about time to add overworld battles/events, and an epic battle against the Henperor itself. That would further the RPG aspect of this game, possibly increasing its downloads on Steam.