Threads of Fate will no longer work in Dragonflight.

The system allows you to level alts in Shadowlands through side quests and bonus objectives without completing the main campaign. However, it will be removed when Dragonflight launches, so all characters that decide to level from 10-60 through Shadowlands using Chromie Time must complete the campaign. However, if you started leveling a character using Threads of Fate before Dragonflight launched, you’ll be able to finish it.

Chromie Time has been updated with Shadowlands. When Dragonflight launches, you can level from 10-60 through the current expansion.