With current plans, they work different than any persona thus far (before you complain, tell me how p2, p3 and p4 shadows are at all the same thing) but have familiar elements. Boss tier shadows are a possibility, but I will have to see where things go.
Edit: also, minor arcana are totally fine, if you feel ambitious enough to work thirteen different cards into one character on top of the suit meaning (remember: number has a meaning, colored by the suit the number is), though you'll have to think extra hard to justify your personae.