Yeah, you kind of have to read between the lines for that.
They just said that all Nintendo games would be downloadable. Meaning games that Nintendo made themselves; not necessarily games that have appeared on Nintendo systems.
They'll have to get the rights for third party games to be downloaded.
It's kind of like how they said for the XBOX 360 that it will be able to play the XBOX's biggest hits. Does that mean it's totally backwards compatible or that it will just play certain XBOX games?
We'll just have to wait and see.