I asked to Zendesk about, and here is their answer to all worries about further support on 2020 edition and possibility of use MSFS2020 Marketplace purchased products/add-ons on MSFS2024:
"Thank you for contacting Microsoft Flight Simulator Support today.
At this time, we are not able to give any additional information related to MSFS2024 that hasn’t been answered in our FAQ.
Will Microsoft Flight Simulator 2024 be a completely standalone sequel, or will it also be offered as a paid update for existing players?
Microsoft Flight Simulator 2024 is a standalone simulator and the next-generation sequel to Microsoft Flight Simulator that launched in 2020. Current aircraft and airports that are in Microsoft Flight Simulator (2020), as well as virtually all Marketplace add-ons, will be supported in Microsoft Flight Simulator 2024.
What kind of support can Microsoft Flight Simulator (2020) players expect to see once Flight Simulator 2024 has been released?
We will continue to deliver our Microsoft Flight Simulator (2020) Roadmap which has content ranging from Aircraft and Avionics Updates, Sim Updates, City and World Updates, and also the free Dune DLC. We will continue to support Microsoft Flight Simulator (2020) post the Microsoft Flight Simulator 2024 launch.
Will all purchases users have made from the Marketplace be transferrable to the new simulator? With very few exceptions, virtually all add-ons that work in Microsoft Flight Simulator (2020) today will function in Microsoft Flight Simulator 2024. Add-ons that were purchased from the in-simulator marketplace will not need to be re-purchased in Microsoft Flight Simulator 2024.
Kind regards,
Microsoft Flight Simulator Support Team"