I like that this Direct helpfully gets a lot of this coverage out of the way before E3.

I'd prefer more E3 time spent on new announcements and stuff like Bayo 3.

Loved that there were parts in the Direct where they showed a new thing every two seconds, instead of giving a 10 minute long explanation for every mechanic like they did with Smash.

Galaxy style! I don't care how, make it happen Nintendo!

If I had to guess I'd say the extra style slot will go to Mario Bros 2 US/Doki Doki Panic.

It would be easier to implement compared to say a Galaxy/Odyssey style and would appeal of a lot of player's nostalgia.

Agreed. I don’t know how it could be anything but. That’s if there’s only one slot. If there are more than two then who knows what we’ll be seeing. How about the side scrolling levels from Link’s Awakening. Haha. Yeah, not happening, but they do use quite a few Mario elements. 

My global sales estimation before the Direct : 9-10M
After the direct : 12-14M

Yep.  There's no denying that this Direct was PR Gold.  Maybe we're all just starved for a major Nintendo release, but that Direct had great pacing and just kept hitting us with revelation after revelation, and judging by the analysis videos on YouTube they barely scratched the surface.  I just keep thinking, too, that this would have really helped their E3 presentation, even if they made it a sizzle reel and shortened it to 3-4 minutes.  They must really want to devote time to other titles that they feel will be as mesmerizing.  That means they've got a whole lot more to share than Pokemon, Animal Crossing, and Fire Emblem.  Or maybe they just didn't want Super Mario Maker 2 to overshadow what they have to share.

I still have hope that the missing blank mode on the right of the "super mario 3D world" could be for super mario 64.

Is it unrealistic to hope this when we see what is possible today with Minecraft  and dragon quest builder ?

It has to be Super Mario Bros 2.  The assets for that are ready to go and there wouldn't need to be too much extra effort put in.  Mario 64 would require a whole lot more reimagining to make possible.  I'm not ruling it out, especially as DLC, but not at launch.  I'm almost positive that they'll announce the Mario Bros 2 tool set to start the E3 Direct just to get things off to a rocking start.  It makes sense with the "2" in the title, afterall.  And it will be one of the playable demos on the show floor.  Obviously I could be wrong, and I don't want to rain on your parade of getting a Mario 64 theme, but I think it would just be jaw dropping to see a return of that forgotten Mario realm.