They really need to. I don't know what's up with Nintendo, but it almost seems as if they are afraid to announce it. Sure, this gen marks the first time all 3 have announced less than a year from launch, but if they aren't going to announce it in Sept at TGS, then when?
Sony announced the PS4 9 months before launch. Now, if they announce it this month, that'll be on par with MS's 6 months. But, if they don't do it soon, they aren't going to have time to hype it, explain the hybrid concept to the masses, or iron out any kinks in their HW/policies that the public may dislike. They're already going to have a time trying explain why gamers should want a gaming tablet/hybrid console that's not even on par with XBO and more in line with being a Wii U Pro.