In an interview with JudgeHype, Ion Hazzikostas revealed that for Dragonflight Mythic+ seasons, dungeon rotations first implemented with Shadowlands Season 4 will continue. In this interview, Ion explains that they plan an 8-dungeon rotation for Dragonflight Season 1, with 4 Dragonflight dungeons and 4 dungeons from past expansion.
In Season 2, this rotation will change, including another set of 4 Dragonflight dungeons and 4 older dungeons. It is currently unknown how many dungeons Dragonflight will offer, but the wording on the interview does make it sound like we will see at least 8 new dungeons in Dragonflight.
No details have been announced on how the old world dungeons will be chosen for the Dragonflight Mythic+ dungeon rotation, but it has been announced that Shadowlands dungeons will not be added to the rotation initially, as Shadowlands is a recent expansion. JudgeHype Interview with Ion Hazzikostas
Mythic+Currently, Dragonflight Mythic+ Season 1 is expected to feature 4 dungeons from the new expansion and 4 old dungeons.In Season 2, there will be a rotation with 4 other Dragonflight dungeons and 4 other old dungeons. Those of Shadowlands will undoubtedly be put aside because they are too recent.
Read more on wowhead.com