Think this could potentially be a fairly dull E3 given that console cycles are coming to an end, without it looking like new systems will be revealed at E3.
Most of the major things likely to be shown will probably be things we already know about but I'm really excited to see more of Luigi's Mansion 3 and to finally get an Animal Crossing reveal. Hoping Luigi's Mansion 3 will be more similar to the first game in terms of structure as I really didn't get on with the mission based structure of Dark Moon. Hoping we'll actually get some solid gameplay and release dates for FF7 Remake and Shenmue 3 too, they've been long enough coming.
Not expecting much other than that but hopefully we'll get some nice surprises, above all I'd love to see Nintendo announce more of its back catalogue coming to Switch, whether it's through virtual console, switch online or full-blown remasters/re-releases. It's Nintendo though so I've learnt by now not to expect too much
It would be interesting if Nintendo did a big twist with Links Awakening. See the way dragon Quest 11 will be playable with 16 bit graphics, too down style? Imagine they showed some more of LTTP as it has been shown then said “We’ve also completely remastered the game in 3D, and you can swap between styles at the press of a button”. Cue the game planning out into a fully 3D BOTW style game.