I'm really just expecting a Zelda U reveal and further information on previously announced games.
You shouldn't expect much more when it comes to the Wii U side, honestly.
Nintendo's January 2013 Presentation:
"We will unveil a new 3D Mario, Wii Party, the first screenshots of Smash Bros., and Mario Kart at E3"
Nintendo's E3 2013 Presentation:
00:56 Pokémon X and Pokémon Y
04:13 Super Mario 3D World - Reveal
07:43 Mario Kart 8 - Reveal
10:56 Wii Party U - Delayed
14:52 2013 3rd Party Releases - Trailers
17:40 2013 Wii U Nintendo eShop Releases - Trailers
19:25 The Legend of Zelda: The Wind Waker HD - Trailer
23:59 The Wonderful 101 - Trailer
25:58 Donkey Kong Country: Tropical Freeze - Reveal
28:54 Bayonetta 2 - Gameplay trailer
31:50 Monolith Soft - Trailer
34:23 Super Smash Bros. - Trailer
38:33 Nintendo E3 Booth Tour
So pretty much, all that Nintendo said was going to be at E3...was actually at E3. The only real surprise (that we didn't anticipate it at all) was Tropical Freeze.
This time around we know we're going to get Zelda talked about at E3...so that's one major unveil. If you throw in the other Wii U first-party releases slated for 2014 (Smash Bros., Bayonetta presumably, Sonic Boom, Hyrule Warriors, maybe Yarn Yoshi / X), that's a good chunk of the conference right there.
This time around I expect a Zelda unveil, a 3DS surprise (Majora's Mask 3DS maybe?) and QoL at the end as the "big" surprise of the conference. I really don't expect any new, major retail Wii U games that we know nothing about to get announced, or any major hardware changes to either platform. QoL is the major "change."