As this video claims that you'll able to visit the Painting World & areas of Oblivion through quests. And also alchemystical combinations can fail like in Morrowind and you can you can shoot Oil Lamps down to set the ground on fire. However, he didn't even link a source. I've sent the making of the video for infomation on this I'll shall post if he replys.
I just got a reply from him
Hey got the info from Here
"Die Dimensionstore ins infernalische „Oblivion" soll es jedenfalls nicht mehr geben. Allerdings wird die Paralleldimension in einigen Missionen trotzdem eine Rolle spielen. Wie das vonstatten geht, bleibt vorerst das Geheimnis von Bethesda."
"The gates to the infernal dimension "Oblivion" are definitely gone. However, the parallel dimension in some missions still plays a role. How this happens remains the secret of Bethesda."