It has been confirmed that Nintendo will not make an appearance at the upcoming E for All convention. Here is what they had to say:
Source
With both Nintendo and Sony out of the picture, it does not seem as if E for All will be any more successful than E3.
Nintendo has chosen not to participate in E for All, as it did not fit into our plans for the year. We wish the participants and show organizers good luck with the event. - Nintendo
Source
With both Nintendo and Sony out of the picture, it does not seem as if E for All will be any more successful than E3.