Forbes journalist Paul Tassi confirmed that all returned content will be available for free to all players, regardless of whether they purchased the corresponding expansions previously.
Bungie plans to bring back some materials from the Destiny Content Vault, including locations, campaigns, and raids. However, restoring more than 25 seasons would require too many resources, so their return is not planned.
Players should also not expect the return of regular events like The Dawning and Festival of the Lost. Bungie is not going back to the previous model of regular Destiny 2 development – the team will focus on old content and the future of the series.
It is currently unknown whether all old Strikes, Crucible maps, and Gambit materials will return. It is also unclear whether the returned raids will receive updated rewards. For example, the return of Wrath of the Machine has not yet been confirmed.
Bungie previously stated that restoring deleted content is just the beginning of new plans for the series.