as we know, long term players have problem with all their monsters. heres a suggestion. every 2 eras, make a new island, every era half way through, increase hab size by 5, and at the begining of every era, add a new level to mythic habitats that cost a lot of gold, come with built in boosts, and represent an era, level 5 is for cosmic, level 6 is for whatever era starts around about 17th december, etc.