As Microsoft Flight Simulator 2024 Steam reviews collapse to ‘Overwhelmingly Negative,’ its developer has admitted it "completely underestimated" the excitement for the game.
For any content you purchased outside of the simulator, the Community Folder will continue to work as it did in MSFS 2020. Any content in your MSFS 2020 Community Folder can simply be copied over to the new MSFS 2024 Community Folder, and the vast majority of that content should work in MSFS 2024.
For any content you purchased in the Marketplace in MSFS 2020, that content will show up as owned in the Content Manager (in MSFS 2024 called “My Library”) at launch for you to use in MSFS 2024, and the vast majority of that content should work in MSFS 2024. This availability does not require developers to sign off on their content.
Remake and rebuy everything of course. Did you expect backwards compatibility? Where’s the money in that?
Except that’s not the case according to the Flight Simulator 2024 FAQ