a wonderful catalyst for Anakin turning to the dark side is him getting so seriously injured, disfigured, requiring cybernetic modifications and sealed suit that it messes with him mentally. what could he do? he can longer be intimate with his wife. she can't help but feel repulsed. he's more machine now than man. but there's Palpatine there giving him hope and his anger keeping him strong. perhaps Anakin's near death injuries were even a result of the Jedi order not negotiating with Sith, Separtists, Mandalorians, etc.
there could still be a duel between Vader & Obi-Wan. but i guess that would be a pretty tall order as a fan edit.