Nintendo has said this current E3 will focus on games coming this year, but I expect one surprise to come at the end -- and that's a new Metroid. Metroid is one of Nintendo's longest-running and most mishandled franchises. Some gamers will argue that point but the fact of the matter is Nintendo has neglected the iconic series and it's struggling as a result.
Of course, we know Metroid doesn't sell well. Every time you hear someone question why we don't get more Metroid games, the reason is pretty simple: it doesn't make enough money. Contrary to popular opinion, Metroid is not as big of a franchise as people think, at least not in regards to sales numbers. The highest-selling entry in the franchise is Metroid Prime on GameCube, which sold 2.82 million copies. Wii Music sold better.
All that being said, I do think there is ample reason for Nintendo to make a Metroid game on the Switch, and I believe the company has been doing just that. Nintendo isn't deaf and the company heard the community the second it announced Metroid Prime: Federation Force at E3 2015. The backlash to the 3DS title was severe and, if they hadn't already known it, the bigwigs at Nintendo would've quickly realized how beloved the series was.
With that in mind, it seems inevitable that Nintendo would have commissioned a full-blown Metroid title for the Switch. This is a perfect opportunity for Nintendo to shed all of the baggage that comes with Metroid and make a fresh start; a new story, a new setting, even a new protagonist.
Of course, that's just one idea. The new Metroid could also be a sequel to Other M or Prime 4.