Think about it. Do you think they want to confuse people who played Oblivion by presenting something alien and different? Please. Cyrodiil is basically going to look like it did in Oblivion. I truly doubt they would want to explain lore intricacies to the regular player. Most people would just be like wtf?
Think about it. Do you think most people are so silly as to not expect the landscape to be different 1000 years in the past? Please.
And even if it is like it was in Oblivion, MK, or Todd, or someone, else will create another reasonable pollination as to why is is that way.
The great thing about the ES series is that it is built on top of Deus Ex Machina devices like Numidium and CHIM that can alter the world in a instant.
We already have
-Time travler's
-Space ships
-Moon colonies
-People being born out of the earth itself
-its been hinted that Atmora doesn't actually exist but is insted a metaphor for the past Kalpa and that the Nord's lack of a creation myth is because they weren't created in this universe but sailed over from the past one.
-All versions of the races gods exist, are the same being, but can plot against each other.
-Numidium has been siegeing Alinor since the first Era even though it didn't start the siege until the late second.