I think we'll definitely see a Metroid game for the Wii U in 2016, probably a holiday title, maybe even with a console bundle. Thing is, I think 2016 will be the last full year for the Wii U, so I highly doubt that we're going to see a Mario Galaxy 3 for the Wii U. I could be wrong, especially given the recent release of Mario Galaxy 2 for the virtual console, but I think that Mario Galaxy 3 is going to premiere as a flagship title for Nintendo's next console. One of the biggest mistakes Nintendo has been making is a lack of good titles at launch to help sell the system and a lot of people specifically point to a lack of Mario going back to the Gamecube days(wheres my Luigi's Mansion U btw?). I don't think that Nintendo intends to make that mistake again. I'd be willing to bet we'll see both F-Zero and Galaxy 3 on Nintendo's next system as launch titles, possibly with a Splatoon sequel as well, depending on how well it sells.
“What I say is, a town isn't a town without a bookstore. It may call itself a town, but unless it's got a bookstore it knows it's not fooling a soul.” - Neil Gaiman