When starting the final story quest from the War Table, the game warns that some quests will become inaccessible after you completing the game, and that you should take care of anything important before starting the quest. Is there a way to tell what quests are unavailable after completing the game?
I don't know for sure, but I'm guessing whatever becomes unavailable is related to the party member that is no longer present after the final battle:
Solas. Watch for the post-credits scene.
If someone has a more comprehensive answer I'd love to hear it.
I know for a fact that a few Inner Circle missions and a few operations will become unavailable. As for which operations, I am not too certain although I think you will not be missing out.