The Elder Scrolls: Online takes place somewhere in the 2nd era, but in Morrowind there was already an eruption of Red Mountain in 1E 668.

However, in videos of ESO, we see Morrowind as a more green landscape -without ash- instead of the ashlands from TES 3: Morrowind.

Thoughts?

1) The game Morrowind took place on Vvardenfell, which makes up bout one third of Morrowind's actual land mass.

2) Vvardenfell is more ashy than the mainland due to Red Mountain.

3) Even Vvardenfell has non-ashy parts like the south west and north east.

This. Morrowind is bigger than just the one island, and with borders on Skyrim, Cyrodiil, and Black Marsh, should have a decent variety of terrain.

Also look at volcanoes like Mauna Kea, Aetna etc. that have all been recently active. The terrain around these is quite green. (Maybe because volcanic ash is actually a good fertilizer ).

Until an expansion pack you will only be visiting one city from Elder Scrolls 3: Mournhold. Other than that don't expect to revisit ANY areas, until an expansion is released.

No Caldera/ balmora/ ebonheart/ vivec, etc.

That's right, you can't go to ebonheart in the ebonheart pact.