For Season 4, there is an alternative option (affectionately?) known as Barexit.
Downtime Activity: Escape the Mists
A character with the Demiplane of Dread story award can gain the Escape the Mists story award after paying 20 Downtime days to leave Ravenloft. The Downtime day cost is modified as follows-
+10 Downtime Days: Touched by the Mists – For each time the character has died, been brought back to life by the mists, and gained the Touched by the Mists story award.
+5 Downtime Days: Enmity of Jeny Greenteeth – A character with the Enmity of Jeny Greenteeth story award (from 04-06 The Ghost) has not only angered the hag, but the mists themselves.
+5 Downtime Days: You Murderer – A character with the You Murderer story award (from 04-08 The Broken One) has killed villagers of Orasnou. The Dark Powers grip on them is tight.
+5 Downtime Days: Cursed by Greed – A character with the Cursed by Greed story award (from 04-09 The Tempter) has given in to greed at the behest of the Dark Powers. Leaving Ravenloft will be difficult as a result.
+10 Downtime Days – Escape the Mists – Each time a character escapes the mists, but then returns to Barovia, escaping again gets progressively harder.
If a character does not have enough Downtime days to escape the mists, they are stuck in Barovia forever. To gain downtime days, a player should play more Curse of Strahd adventures or be a Dungeon Master to gain DM rewards (Downtime) to award to a character to escape Barovia.
Ending the Death Curse
For Season 7, the Death Curse will end for any character who wants it to end after Tier 3 content is published - this is detailed in the Adventurers League Players Pack. The catch is that a character who opts to "wait it out" can then never be used in Season 7 Tier 1 or Tier 2 content or the Tomb of Annihilation hardcover. In effect, those missions were done by "other people" and the character's personal timeline has advanced beyond that point. (DDAL timelining is a little wibbly-wobbly, but them's the breaks.)
The Death Curse in Barovia
A character who is subject to the wasting effect of the death curse (i.e. has previously died, and is losing maximum HP) is still subject to it while in Barovia. However, a character who has not died and has the death curse cannot be consumed by the soul monger - it doesn't reach across planar boundaries. Such a character (assuming they are raised while in Barovia) will begin to waste away when they return to the Realms.