Bethesda and others reading, i think you should be able to re-visit skuldafn - an area you discover in the main quest by riding a dragon. I think this because when i did the quest for this area i missed a shout and dragon mask. And since I can never return, i will never be able to retrieve those things.

What you could do, is you could make it so when you called your dragon you could talk to him and he could take you there. Or maybe you could learn a spell or shout to return to the area. You don't have to worry about Sovngarde but i was hoping it would be possible to return to Skuldafn