If you want all the future content available for purchase at this time, then you want the Shadowkeep Deluxe. It includes Shadowkeep, season 8, season 9, season 10, and season 11. The basic Shadowkeep only includes Shadowkeep and season 8. Both include New Light at no extra charge (Destiny 2, Curse of Osiris, and Warmind), simply to make it easier for newcomers to make a single purchase and get everything needed to play instead of having to purchase one product (Shadowkeep) and then go to a totally different product page for New Light to purchase for free and download. You already owning the New Light content will cause no issues; your licenses will simply overlap with each other; you'll not be forced to download a new copy separately for Shadowkeep.