Question about whether or not a controller breaks are valid, but why is everyone freaking out over local mulitplayer? If the Wii U has a competent online infrastructure (though whether or not the Wii U will have this is still to be determined) this won't be an issue. The amount of times I've played local multiplayer on my 360 is in the single digits, and that's how most people will want to play multiplayer for more hardcore games, such as CoD and such.
As for party games, similar to Wii Sports that made the Wii a posterboy for families playing local multiplayer together, chances are thing will stay the same. The Wiimotes work with the Wii U, so most family and casual party games will just pass over the new controller entirely to cater to an audience that already loves playing Wii games with the Wiimote. Similar to how most multiplayer Wii games only used the Wiimote because very few people owned multiple nunchucks, the Wii U will probably base multiplayer heavy games on the Wiimote or online play.