The WiiU will most likely have all these features...online, music playback, dvd, video, w/e.
The 3DS has music, video, online, etc. So, you can only assume the WiiU will as well.
Not to mention, Nintendo has emphasized online multiplayer with the WiiU, saying they've worked very closely with developers to make a good online experience.
So, It all sounds wonderful, and I can only hope it is.