I don't know if the Wii will beat the DS next year. This year, the DS will sell 21-point-something and the Wii 18-point-something. The Wii is likely to see a small drop next year, to 14-18 million. Let's say 16 million for the ease of it.
Is that impossible for the DS? It's likely to see a price reduction at some point next year, so I'd definitely say that it isn't. It's also getting another main-line Pokemon game releasing for it, and that should help sustain its sales.
The GBA had one of its biggest years after the DS launched. I don't see why the DS shouldn't be able to do the same with the 3DS.
I'd also say it's unlikely that the 3DS will sell as much as the DS next year, though. It has some fierce competition from the DS.
Wii = DS > 3DS seems more likely to me. The rest of your prediction seems fine, though.
