My understanding is:
- If a customer owns a 2020 Marketplace product, that purchased product will be available in MSFS 2024 in their My Library on day 1 with no intervention/sign-off from the developer. In other words, anything you own in 2020 is yours in 2024, too.
- If you, the developer, wish to make the product available for purchase in the 2024 Marketplace, then you need to go through the sign-off process.