According to Trellia and the future Asterite, this was supposed to be the Earth's natural future before Ecco traveled back in time during Ecco the Dolphin and altered the timeline by bringing the Vortex Queen to Earth. However, how this future was brought about is not discussed, as the Earth could never recover with the constant Vortex attacks.
In the good future, Earth and its biosphere continued to grow and evolve. It appears that on land, nature had recovered and made the land green again. At some point the oceans of Earth seemingly 'woke up' and became sentient, developing a consciousness. Apparently the rise of this new consciousness had the effect of creating vast, floating water tubes in the sky that connected the various waters of Earth to each other. These tubes are neither entirely contiguous nor are they completely solid, as air holes are prone to opening up in the tubes at times. However, this new avenue of mobility for aquatic species eventually gave rise to several new species in addition to altering existing species in various ways.
One of the species that underwent significant changes was the bottlenose dolphin species which developed internal helium sacks which allowed them to fly, expanded fins for manoeuvrability, and the ability of telekinesis which allows them to move objects with their minds. It is unknown if other members of the Delphinidae family, whales, and porpoises developed the same abilities and physical changes or different ones as they were not depicted in the game.
One of the most terrifying creatures found in the good future is the massive floating medusas, giant jellyfish that had also developed the ability of flight, and now seem to live amongst the various sky tubes, perhaps to prey on travelers, or purposed as guardians. Unlike most regular jellyfish species from the present, they are far more active predators, pursuing intended prey, suggesting that their intelligence has also increased along with their mass. Their presence is likely the reason why the skyways are devoid of all other life forms.
Strange creatures or plants with trumpet horn like extensions also came into existence, in general not being dangerous as they are stationary, they would release a clould of poisonous bubbles when another creature came close to them.
From what can be seen in the game the human impact on Earth has been severally reduced or never spread that far as various rich jungles can be viewed from above in the skyways. However there is no proof that humans exist in this timeline either. As humans are never brought up in the Ecco the Dolphin games it is unknown what the fate of the human species was in the good future, perhaps either having gone extinct, migrating to another world, or perhaps intergrated with the changed biosphere in a more harmonious way.