It'll be nice to get a good Wii U focused Nintendo Direct.
But honestly, I don't think game announcements actually cause sales spikes. Unless they are sitting on something massive like Final Fantasy XV being exclusive or something, I can't really even see a console comparison to getting Monster Hunter exclusive for 3DS.
Like it would have to be something huuuuuuuuuuuuuuuge.
Showing off Mario Kart U, Bayonetta 2, Wonderful 101, etc. will soothe some concerns, but I doubt it causes a huge sales spike.
That said, at this point every bit helps. They should go ahead and have a big Nintendo Direct this month and show off Bayonetta 2, Monolith's RPG, more on Pikmin 3 and Wonderful 101, then another Direct in Feburary or March showing off Mario Kart U.
Save 3D Mario and Wii Sports U for E3 along with a Super Smash Bros. trailer.
