GameCube, but the 3 Game Boys would happen first.
The GameCube is sorely needed because it has never been on Virtual Console or something similar (even the Wii had digital games on the Wii U). Also, GameCube games are really high in price online. Granted, that's not a uniquely GameCube issue.
GCN, Wii, and Dreamcast are far and away the most unlikely of the options you gave. I would not put it past Nintendo to have a third tier (an expansion of the expansion pass) for those platforms.
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
