Here are my current thoughts:
- Spirits were made to compensate for characters who missed the base roster for Ultimate.
- Ultimate has currently gone gold, which theoretically means that Spirits were only made to compensate for the base roster for Ultimate.
- Some people may think that since Nintendo is picking the DLC, it spells more misfortune than if Sakurai chose DLC....
I disagree, but only in a sense.
If Sakurai was choosing the DLC, then I highly doubt that he would pick any characters that were made into Spirits. Since, like I said, Spirits were made to compensate for characters that didn't quite make the roster. Instead, Sakurai would shift towards characters who weren't included in Ultimate at all, since I highly doubt he would backtrack on his work if he himself practically set it in stone. You could argue that characters such as Lucas and Mewtwo were made into fighters after being displayed as trophies back in Smash 4, but I highly doubt that Spirits are supposed the function exactly like trophies. Spirits are much more than just collectables, since they even have their own designated Spirit Battles.
However, we now know that Nintendo is the one picking the fighters instead of Sakurai, and although Sakurai gets the final word, he said that fighters will be chosen based on if they have enough potential for a moveset. Unless he was hiding specific rules about what fighters can be chosen, this practically opens the floodgates to practically any character, regardless of his/her status in Smash (at least in my view). This could allow Sakurai to backtrack on certain characters and allow them playable status. All he needs to do is make a Fighter Spirit out of the character (since Fighter Spirits can return to the "real world"), and he doesn't need to remove the regular Spirit since there will be some form of differentiation between the two. (In Bandana Dee's case, they could just use a newer render of his character for his Fighter Spirit).
Although, in order for us to get lucky, Nintendo would have to request characters that have a large amount of popularity surrounding them, rather than promotional material. They could easily give us a mix of fanservice and promotional characters, but we'll just have to see.
TL;DR, with Nintendo picking the DLC characters we have a better chance of getting Dee, under certain conditions however, in comparision to if Sakurai was choosing DLC characters, at least in my view.