Sony and Nintendo have different approaches, Sony tend to announce game few years in advance while Nintendo is looking to have less time between announcement and release.

Yes, Switch is huge succes and Nintendo cant keep up with demand, and more big and system seller games or on way that will continue momentum and increase demand for Switch on market. Switch is selling better than GC in same time, and GC never had sucha demand that Nintendo couldnt keep up with it, and Nintendo very clever scheduled their big and stronger games, so that we have one stronger or bigger Nintendo game every month.

If talk about 3rd party, after Wii U most of 3rd parties take "wait and see" approach with Switch, they waiting bigger instal base and to see how much exactly success Switch is. I expecting to see much more 3rd party games around E3 next year.

MK8D is remaster, but Splatoon 2 is full sequel.

So reasons for Wii U owners to buy Switch this year: ARMS, Splatoon 2, Monster Hunter, Mario x Rabbids, Fire Emblem Warriors, Mario Odyssey, Xenoblade 2, various 3rd party games. All this games are not availible on Wii U, offcourse there is point that even games like Zelda BotW, MK8D and Pokemon Tournament DX gave better expariance on Switch than Wii U versions and full portable mode for playing (thats alone is game changer for some people).

Its very obvious that Switch doesn't have anything with Wii U, Wii U sales tanked less than 2 months after launch and didnt had any stronger or bigger games that could raise sales, with Switch we are not more than 3 months after launch and its still selling good and Nintendo cant still keep up with demand, while more big system seller games are arriving in near future (Splatoon2 next month). Not to mention things like marketing and perception that are for Switch great and totally opposite than they were for Wii U.

Ninty is ALWAYS d0m3d, whatever it does! B0rn to be d0m3d!

E3 is irrelevant to the success any platform has on the market always has been hence why Nintendo treats it like the passing day dream it is even third parties are starting to do the same. The whole doomed scenario is something that goes all the way back to the early SNES days, even early this year we had that thread about how they should go third party and the Switch would flop.

I think they need a couple of high profile announcements for 2018, but Switch's line-up for the rest of 2017 is already solid, even without further announcements. There's enough software for a first party release every month from now on:
June- Arms
July- Splatoon 2
August- Mario/Rabbids
September- Pokken Tournament DX
October- Fire Emblem Warriors
November- Super Mario Odyssey
December- Xenoblade Chronicles 2

Add to that ongoing sales of Zelda, Mario Kart 8 and 1-2 Switch, plus some major third party brands: Skyrim, NBA, FIFA, and smaller tier releases from indies and third parties (e.g. Western release of Dragon Quest Heroes), and Switch has plenty coming for a system in its launch year.

Nintendo don't need to go all out and announce projects years from fruition. That might generate hype, but it's not going to maintain sales momentum, which will come from regular first party releases, a gradually diversifying library, and building up key features, such as online. On top of that, we've seen continually that Nintendo sticks to their own schedule for announcements, including revealing Switch in October, before revealing launch details and some 2017 software in January, without damaging Switch. If anything, Nintendo's strategy so far with Switch has been solid.

Nintendo do need to demonstrate some 2018 software, but concentrating in detail on the next 6 months of software, while sketching out the 6 months after that, is actually enough for them. Switch is off to a solid start, with major Nintendo brands available and coming soon, and its first Christmas season ahead of it. Nintendo are in a pretty solid position this year, and E3 isn't going to make or break that.

You speak as if Nintendo always wanted to show things that were ready to come out soon.
When they had stuff to show in advance, they showed it (E3 2014) and when they didn't have (E3 2015), they didn't show it.

But this was not my point.
My point was that doing things like Sony's - and even MS - way is doable and when i try to understand how NIntendo went and did something different, i realise that they didn't do it because they couldn't.
I'm not against doing things differently, i'm surely not against doing things in a short time frame, but i'm not blind: Nintendo did not have enough to show in 2 presentations (the focus on 2017 games at this E3 shows that). So what do they do? 1 presentation before launch and that's it.

I may be wrong, but i honestly don't see anything that clearly shows how doing what Sony did could have been a serious option for Nintendo. That's all.

From what i remember reading, GC actually had a good start: good price, good 1st party support... until that support kind dried up.
It's too soon to determine if Switch won't go the same way even if Switch has way more demand than GC. If the support isn't there next year (we don't know that yet), sales will fall.

Big userbase won't necessarily mean more 3rd party support.
Just look at how 3rd parties pretty much avoided bringing their best games to Wii. Why? Because, despite the size of the userbase, the audience for their games simply wasn't there.
Naturally, the bigger the userbase is, the more people can buy your games.

This has been Nintendo's problem since GC: grow userbase and 3rd parties will come.
It just doesn't work that way.
Nintendo needs to show that 3rd parties can sell their games, but to do that, they need to bring those customers first (1st party shooters, racers, etc.; exclusive titles in popular genres, for example.).

Wait, so it doesn't matter how well a game sells, if it's not in the top 10 on the platform and Nintendo games sell better than it than it's not successful?

On GameCube: the system came out right at Christmas and had drougts right after; not to mention Sony had a much more popular machine with tons of momentum (including full 3rd party support behind it) before GC even launched.  Lastly! it's not a handheld.  I don't think there's a good comparison here at all.  Nintendo has already addressed softwarefor the first8-9 months of release.

On 3rd parties! I do believe building a big user base will pull them in! look at DS.  Wii might be the counterexample! but I think the industry had a  bit of an agenda against Wii! and in fact! it did have more million selling 3rd party games than the competition - at least for a couple of years.

But I agree proving third parties can sell is a bonus which is probably why we're seeing the "weird" lineup that we are.  Who knewBomberman could push 500000 units.  Dkyrim should do great 

Not always, but they changed their approach last few years, they several times said they don't intend to announced games that can't be out few years, and we already saw they anncuing and relasing games in less than a year. Like I wrote different approaches, Nintendo could easily choose to show lotsa 2018. games on E3 but instead they said they will focus on 2017. games.

Best GC year in sales was 2. year of GC on market (FY year that ended Mar 31, 2003.), and GC sold 5.76m in that best year. Switch will most likely just in 1st year on market sell around 10m. Like I wrote, Switch is selling better than GC in same time, and GC never had sucha demand that Nintendo couldnt keep up with it, and Nintendo very clever scheduled their big and stronger games, so that we have one stronger or bigger Nintendo game every month. Also what's different with Switch compared to GC is that Switch is also handheld in same time, so it's basically aiming at handheld market in same time. Offcourse there will be good support next year too, Fire Emblem, Retros game, Next Level Games game, Animal Crossing, Pokemon, Smash Bros, Pikmin 4, some other Wii U remasters, some new games...all are possible for next year.

http://vgsales.wikia.com/wiki/Nintendo_GameCube

Actually it means, bigger user base means more 3rd party games compared to small user base if we talk about same platform. Wii actually had probably best 3rd party support for Nintendo console from SNES.

On Switch 3rd parties could actually have much better sales compared to past Nintendo consoles because now they can played them in full handheld mode also and thats for some people game changer.

The GC comparison served a purpose: even if you have a great start, that doesn't garantee that that success is garanteed. You have to keep that momentum. And so far we have nothing showing that Nintendo will be able to do that.

There was no agenda against the Wii.
The userbase simply wasn't the same you had on XB360 and PS3. And in the end, that's the most important thing: who am i sellng my games to?

Sony and MS do what Nintendon't! :)
Their games are the same type of games that 3rd party make. Even the marketing/strategy goes in that direction; Nintendo doesn't make that type of games, no their strategy goes exactly that way. Therefore, Nintendo doesn't attract PS4/XB1 fans.