If Nintendo does not give Americans more than some mediocre Tennis game it will fall even more, and we will see the 3DS and Vita fighting for the 3rd spot in America soon. Where the hell are all the games for Americans! For Europe!
What do you want them to do? They slashed the price, they released two of their most strong titles already, already announce it's biggest title which is coming this year, and will release some others as Luigi's Mansion. I mean, the situation is indeed worrying, but, they took a hit just to increase the market penetration, and are releasing games. They also have the launch of WiiU soon, one can only wait for third parties to step up, or somebody to create a "Brain Training" effect.