Youtube user "Candyland" has posted a very cool video comparing the original TES 3: Morrowind visuals to the new version that will launch with Elder Scrolls Online: Morrowind. Similar locations from both games are shown side-by-side for easy comparison.
The Elder Scrolls 3: Morrowind originally launched in 2002, while the ESO Morrowind expansion is set for launch in June 2017.