Animal crossing would be my guess. Nintendo did put dome Pokémon direct close to E3 the last couple years, and I think they will do that again this year.
Unless Fire Emblem is not yet released by then, as this one could be a big focus, too.
The Nintendo eShop rating Thread: http://gamrconnect.vgchartz.com/thread.php?id=237454
The Steam/GOG key gifting thread: https://gamrconnect.vgchartz.com/thread/242024/the-steamgog-key-gifting-thread/1/