If Platinum Games makes it, odds are a lot of it could be cinematics.

Miyamoto said that they were doing amazing cinematics for this game. We also know that the game is going to be playable for the press, so they can show something more cinematic first and later the press will cover the gameplay.

It's still Star Fox and still co-developed by EAD, partly helmed by Miyamoto. They could get Quantic Dream to make the game for them and I still wouldn't expect an abundance of cutscenes. It's easy to make "cinematic" moments without cutting away from gameplay in an on-rails shooter, there's really no reason to have cutscenes at all.

I can even see them agreeing that Nintendo will show off the gameplay, and PG will show off the cinematics.

They're going to let Platinum Games do whatever they want. I can pretty much promise you that. Not to say it is Star Fox, just a feeling I got. But it could be Mario Universe and Peach could show up completely naked and I doubt Nintendo would care. Have you seen Bayo or Devil's Third? 

Where did he say that? I see him saying that the gameplay will look cinematic and impressive. "...when you wanna see the really cool cinematic visuals as you’re playing, you’ll look up at the TV screen and when you want to get really serious about battling an enemy, you’ll look down at the cockpit view." The cinematics are during gameplay... maybe they will show the "TV screen" footage during the DE, and let IGN show the GamePad footage? Would be kinda weird but might work?

Let's not exaggerate. I think Nintendo would care a little bit about that. I have seen those games, have you read the Iwata Asks for Bayo 2 where they said they wanted to polish the graphics some more but Nintendo told them it looked fine and they should focus on the gameplay instead?

EDIT: It wasn't an Iwata Asks, it was actually an interview with Gamasutra. "And all of the things we want to do in the game, [Nintendo is] not standing in our way, in that sense. But it's almost as if they are a very critical player that can sit back and give us great advice on how we're creating the game. [...] one thing that comes out of that is that we're not able to cover up weaknesses in the core gameplay by making the graphics prettier or adding cutscenes, or whatever. The concern, first and foremost, is the core of the game and the quality of the gameplay."

I'm guessing Viewtiful Joe 3 for the Wii U, published by Nintendo.

Don't forget:

Here are Kuroda’s full words:
“I have started working on the next project, but it looks like the announcement will come later. In any case, I think that it would be nice if something Bayonetta-related was also developed in 2015, so please pay attention to the continuation of Bayonetta!”

I am tremendously excited.

Just one thing : the time of this "gameplay" is after all the conferences, so it means it will be revealed before IGN lays their hands on it, right?