Nintendo doesnt attend TGS usually ,so I woulndt expect too many announcements there.Besides ,most hardcore Wii games have flopped badly so I doubt the developers are eager to put too much effort behind it.As it is cheap to develop for it will get some games ,specially given the casual market there is right now.And some spin offs of major franchises.
As for E3 Nintendo must have something to announce.If not they would be without a single game worth mentioning for all the remaining year and since Mk Wii and Smash Bros ...that would be the total amount of Wii good games for the year at two.Most of their major franchises are already out ,but they still have FZero ,Pikmin ,Starfox(although they havent ever developed a Starfox games themselves ,the first were Argonaut Software ,Starfox Adventures was a Rare project and the last one was developed by Namco ...I have some doubts with Lylat Wars).But not even one of these would make a great impact.But if they announce Wiintendogs or something like that they would keep selling like hotcakes to the current market that is buying their products.Theres too the possibility of Wii Music or something in the line.