The announcement as given by the OP and the Nintendo Twitter account says...

OP: "We’re having a Nintendo Direct tomorrow to provide updates on upcoming summer Wii U and Nintendo 3DS games"

Twitter: "Join us tomorrow at 7 AM PT for a #NintendoDirectNA to provide updates on upcoming summer #WiiU and #3DS games."

It does not says first party only anywhere, but people seems to be expecting only Nintendo games, these presentations are a great way to show the third party games and support the efforts of the ones who are doing a decent job on the console, don't spend 50% of the video on them, but mention them with a release date and highlight the use of the gamepad or any extra feature even if it is a simple one.

I do hope that Nintendo spends sometime on the third parties, 5-8 minutes could be enough, give me a release date for Deus Ex, show me the use of the gamepad for Resident Evil, and mention all the third party games that are comming in the summer for the Wii U, because otherwise as somebody said before "nothing is comming for the console" and it needs to show that the flow even if it is a thin one, is there.

if you want to know how RE-R plays check some 3DS videos. it's likely they are exactly the same

Dear God.

Whatever did happen to that promised 3rd party WiiU direct anyways?

Did people bail out like they did with 3DS? (Seeing a trend here.) And now they missed an opportunity.

People are really all too eager to drop Nintendo.

I think a different force than God was responsible for that...

GTA5, my bad.

I've held off buying a 3DS because of poor battery life and bad colour options (In North America) for the 3DS. I got by without Fire Emblem, now there is nothing that will make me buy a 3DS before a redesign. It's silly yes, but I still play my original DS, so I need one with a battery and colours which work for me.

Oh perfect! I recall hearing Nintendo say that Wind Waker is an August release, but it would be nice to get release dates for Wonderful 101 and Bayonetta 2 as well. W101 was suppose to be a launch window game, so if it releases in fall, that would really surprise me.

Plus any info on Smash Bros., Mario Kart 8, and Super Mario U would be nice.

People don't really pay attention--to those of you who are expecting ANYTHING on 3D Mario, Mario Kart, or Smash Bros. tomorrow, or even Bayonetta 2 or Wind Waker, you didn't read the original post. It says SUMMER Wii U and 3DS games, and right after that it says FALL and BEYOND games will be talked about in a Direct at the time of E3.

Anyway, I'm excited for this, even though my expectations aren't super high. I'd be surprised if there were any NEW titles or previously unconfirmed 3rd-party titles announced. I'm thinking this is more of a "previously announced/shown" Nintendo Direct so that the one at E3 can be all the NEW games with NEVER-BEFORE-SEEN footage. If they tried to do both in one Direct it'd be like an hour long, in which case, why not just do a press conference? This way we get stuff like Pikmin and TW101 out of the way ahead of time so the E3 Wii U Direct can be completely NEW stuff. I'm expecting something along the lines of:

For Wii U

Another Game and Wario Trailer or footage with mention of the lower $40 price
Pikmin 3 Story Trailer
Wonderful 101 Trailer AND Release Date

Resident Evil: Revelations Footage
Deus Ex Footage
Splinter Cell Footage
Disney's Planes Footage
Maybe mention of Disney Infinity
Maybe a Rayman Legends Trailer
New Super Luigi U Release Date

For 3DS

Mention of Donkey Kong Country Returns 3D release
Animal Crossing footage and release reminder
SMT4 Trailer
Rune Factory 4 Mention
Mario & Luigi: Dream Team Trailer
Mario Golf: World Tour Trailer and Release Date

If Reggie appears at the end there will probably be a surprise of a 3rd party game OR possibly a September release date and a trailer for The Wind Waker HD.

I'll be at work, I will be watching your nintendo official threat for news during the day my friend!

Boring, only summer games...