Currently Online 
It's not cost-effective yet.
All the mini consoles have been Gen 5 and earlier. Xbox didn't enter until the sixth gen. Even 10 games on an Xbox Mini will at least rack up an $80 price tag. Probably higher than that.
Maybe once other mini consoles have come out and maybe after Nintendo 64 Classic, an Xbox Mini might make sense. I could see them including it with a Duke as well, or having the Duke as an optional accessory.
Lifetime Sales Predictions
Switch: 151 million (was 73, then 96, then 113 million, then 125 million, then 144 million)
PS5: 115 million (was 105 million) Xbox Series S/X: 57 million (was 60 million, then 67 million)
PS4: 120 mil (was 100 then 130 million, then 122 million) Xbox One: 51 mil (was 50 then 55 mil)
3DS: 75.5 mil (was 73, then 77 million)
"Let go your earthly tether, enter the void, empty and become wind." - Guru Laghima
