Its Important to have paid editions additional to the base sim, to have more content availability beside the free content.
my guess is that there will be two paths possible for the MSFS 2024 Deluxe & Premium Editions:
1- offering 2020 Deluxe & Premium Editions content (aircraft & airports) as a standalone products for 2024 to purchase, with maintaining current ownership for those aircraft & airports for 2020 Deluxe & Premium Editions owners. so MSFS 2024 Deluxe & Premium Editions will be new Catalog entirely.
2- keeping the current 2020 Deluxe & Premium Edition content for 2024 Deluxe & Premium Editions, but extending the catalog, to include more aircraft and airports, or even new element other than aircraft & airports in addition. so even owners of 2020 Deluxe & Premium Editions, will benefit from buying the new Deluxe & Premium Editions extended catalog.