They did the exact same thing with Pokemon Black/White. Those games were released in Japan around September 2010 on DS while the 3DS came out around February 2011.

Plus they have to release future Pokemon games on NS. The 3DS will only last so long. It's a very old system now and Pokemon Sun and Moon are its swan song. Given that there is little to no indication that Nintendo will release a 3DS handheld successor, it is safe to believe the NS is the successor. The next Pokemon games will have to release on that console, or the franchise has nowhere else to go. 

And please don't say mobile. No, just no.

I could be forgetting something, but I'm assuming you're talking about the Mario game shown in the Switch trailer. If that's the game you mean, I wouldn't still consider it as having been shown yet because it was no reveal for the game. It hasn't even been admitted to exist yet. And personally I think Nintendo will want to stick to handheld development as long as possible, mainly because of lower development costs. You have good points though, I just don't agree with them personally.

Indeed, when handheld 3DS games meets a more powerful console..

But it does exist! We all saw it! They just haven't talked about it yet.

Longer than one more year though? This is just my speculation but I doubt the 3DS is gonna do that well next year with it's current line-up and NS as competition, and 2018 is just gonna be worse. More games will probably be announced but I'm honestly hoping the ones we know of are the last. It's definitely safe to say that 3DS has nowhere to go but down while the NS naturally needs a lot of games especially early on to be successful.

Also NS being an HD system doesn't mean every game on it has to have a triple A budget. Nintendo has already made HD games that can sell for the price of 3DS games like Woolly World and (in areas outside the U.S.) Splatoon. This should be even easier to do now that they're familar with this level of hardware and already have assets n engines n stuff. But yeah, you don't have to agree with any of what I said, I'm probably gonna be dead wrong as per usual anyway. :L

It could be interesting. Though it may take a long time because you're considering HD (which I'm not sure if Game Freak has dealt with before), over 800 Pokémon, multiple regions, languages (not sure how other games dealt with having Japanese, Spanish, Chinese, English, or other languages being considered) since people here want voice chat, and how they have to avoid the pitfalls of previous MMOs and RPGs that are vast and expansive.

Nintendo could still consider it as an unrevealed game. For all we know, that could be just a tech demo and not an actual game.

I'm kind of expecting Nintendo to release yet another handheld, but I think there's a lot of uncertainty about that. If there is another handheld, Nintendo is sure to support it. I'm not really expecting Nintendo to support 3DS very long anymore though, at least in a big way. Anyway, 3DS is still a profitable system, and I don't think Nintendo is in a rush to get rid of it either. And because of NS's size, I'm not really expecting it to compete with 3DS anyway. It's going to be especially bad for NS if it doesn't have good battery duration.

I don't think releasing graphically subpar games is something even Nintendo wants to do. Not everything has to have a huge budget, but developing for Switch is sure to be more costly than developing for a potential future handheld. It's an interesting situation though, since the graphical capabilities of portable devices have increased a lot since 3DS's release. The difference in cost might not actually be as big as I think.

Don't worry, I could be wrong too. I think there's a lot of uncertainty about what Nintendo is going to do, and I'm just leaning towards them releasing another handheld. If this was anyone else than Nintendo, I'd almost certainly agree with you, but this is Nintendo we're talking about.

Blame the fools over Game Freak for that.

The other games shown alongside it were actual games so I highly doubt that, but eh this is really getting besides the point, being that Nintendo is far from always truthful.

Now that would be suicide! Nintendo couldn't adequately support 1 SD system 1 HD system, really can't see that working with 2 HD systems. And although NS may not fit in your pocket it's still a portable that get's Nintendo games so it'll be the 3DS' closest competition. That's also why a 3DS successor doesn't have much use, there's very little reason for one while the NS exist. I have to say this would be a monumentally tremendous mistake, but we can't know for sure until it happens so we'll have to agree to disagree here.

You're contradicting yourself there as handheld games are graphically subpar, so to make more handheld games means to make more graphically subpar games. Plus a 3DS successor would have to be HD so there would be little difference in cost.

Understandable, I should probably take a similar stance as well after the many times I've been wrong but I'm too stubborn. If something seems logical to me I stick with it to the bitter end!

Miyamoto is different from Nintendo. Something Nintendo says wouldn't necessarily be the same thing Miyamoto says.

Nothing about that Mario game looked any different, so I don't think that was the game they were talking about.

lol whut? Nintendo isn't a person or individual that says things for itself, it's a company made up of tons of people including Miyamoto. When we say a company has said something, we mean the people within it said it, not that the company is literally talking! xD

Only time will tell!