We're happy to announce that you can indeed upgrade to the next-generation version of the game, for free!
Here is a guide on how you can do this:
For digital copy owners who purchased on the Xbox Store, you will be able to access your upgrade by simply logging into the relevant store on your next-gen console with the same account that you used to purchase the game for the Xbox One.
For physical copy owners, you will be able to download the next-gen version on your Xbox Series X when it becomes available as well. To do this, you need to insert the disc into your console to be able to play. This means that you will need to have a next-gen console that can use discs.
PLEASE NOTE: You can only upgrade from a physical current gen copy to a digital next-gen copy if you have a next-gen console that you are able to insert a disc into. When you do, you will be able to download your next-gen edition, but will still require the disc to authenticate and play.