As far as I know, at least from experience, there is always a version update whether you buy that expansion content or not. Everyone is always on the same version of the base game, and the update is required. It’s just the new content you won’t have access to if you don’t buy the expansion. Basically, just like what MSFS is doing now. You don’t have to download the new world update content, but you do have to be on the current version of the base game.