I would a handheld that would let me play older pc strategy games like Heroes of Might and Magic III, Civilization III or IV, the Master of Orion games. I think handhelds are great for turn based strategy games and Nintendo should work on getting some PC ports on their handheld.

Handhelds are mainly to play games in the same position you read a book, to play games in bed. I am sure most people with handhelds mainly play them at home. You don't beat Pokemon, Etryan Odyssey or Bravely Default outside your house.
That you can play them outside your house is a bonus, not the main thing.

The core 3ds market were once kids and are now mostly in their 20's and 30's. Sony didn't have a long time handheld history.  It's only 1 of many reasons the vita failed. 

This, that crowd are the group who say they'd rather have a said game on console and in the end this is the root of the problem that has hit Vita, it's predecessor tried the same approach and ended up selling for far different reasons. As handhelds go a broad approach is always best.

I'm a huge Nintendo fan, but I don't really think they do target teens in the same way they target young gamers and lifelong gamers.

I think you're missing one very important point here: iPad is very popular among kids because EVERY house hold has one! That's how kids come in contact with it. They don't see the ads, they see that every family have one. And that's never gonna happen with a handheld gaming device. A gaming device will never become as cool as an Apple product because gaming is somewhat "niche" when compared to the universal appeal of an iDevice. The best selling gaming systems ever sold 150m each over the course of 5 years each. How many iPads/iPhones have been sold in the same time frame? I think that's one of the key things as to why these devices are considered cool among kids; they're new things and they are quite wide spread.  In 5-10 years time they won't be the coolest things around. By then, it'll be an old idea. A tried concept. No one thinks TV's are the coolest shit around anymore. But they used to be. As were the radio when that first hit the market.

Targeting adults with ads as to also sell to kids only works if the thing becomes widely popular, or else the Vita would be the best selling portable gaming device around now, and PSP would have beaten DS.

They need to logically evolve the 3DS, one of the reasons the Vita doesn't do so well was the initial high cost of development.

A bump up to a 720p top and 480p bottom screen would be logically, you can do more with decent processing power and the battery won't take as much of a hit if they would opt for something like a 2K/1080p config. And the touch screens needs to be resistitive, not capacitive for obvious reasons.

I hope they definatly use an ARMv8 chip, but that seems likely, with the speed of advancements in ARM technology, the next handheld wil definitly be worthwile power wise, just don't expect costum high-end ARM cores. As for GPU's, there is a lot of choice for mobile GPU's, from the basic Mali and Adreno graphics to Power VR.

As for RAM, with LPDDR4 around the corner, and the 3DS's lifecycle not at it's end, it's reasonable to guess that's what they'll adopt. Probably not a lot of RAM, but the higher bandwith will help a lot. I'm guessing a 2GB LPDDR4 config.

Don't expect a powerhouse, it wouldn't be logical, but with some specialised hardware, I'm sure Nintendo will deliver us something good.

Note, this is all just speculation on my end.

You're assuming that future Nintendo consoles would still only sell 30-35m units if they targeted core gamers with GC, which is a fault on your behalf.

Let's except your scenario; GC sells 30m units, MS takes a large chunk of the FPS market and tries to paint Nintendo as kiddie. First of all, with almost 10 more million units sold, 3rd party games would have sold way better (I base this on two reasonings; first, there's 10 more million costumers, and secondly, almost none of them are Nintendo fans - since they already bought GC and are included in the 22m units that were actually sold), which could mean that GC would retain exclusivity on franchises like Resident Evil - which could even mean more 3rd party "hardcore" titles (since 3rd party games would sell more). Nintendo would in anyways almost certainly get more 3rd party games to GC.

Even though a large chunk of the FPS market would go to Xbox, Nintendo would still have PD2, a "mature" Zelda (something like TP), mature 3rd party games and maybe something aking to Mario Galaxy. There is no way for MS to paint Nintendo as kiddie then. Nintendo would simply show more mature titles in their commercials - like PD2, Zelda TP, RE4, Star Wars, Eternal Darkness and other games to debunk MS's claim of kiddieness. They could maybe even get a chunk out of MS's 25m Xbox's.

All of this would probably lead to better 3rd party relationships, so when Nintendo kept up with Sony and MS in the specs wars, they'd also get much better 3rd party support. They'd get multiplats, just like PS3 and X360 would have. They would probably have sold a lot more consoles than 30-35m in the 7th gen. Let's remember that both X360 and PS3 are both closing in on 84m units each. If MS could take advantage of Sony's initial failure with PS3, so to could Nintendo. And let's remember that Nintendo would automatically get 10-20m sales just because of its fan base, and with a competative console with good 3rd party support they could easily have gotten quite a few more millions sold.

While production costs would have gone up, so would also Nintendo's revenue. They'd sell more units of their own games PLUS they'd get a lot more 3rd party royalties, and they would sell alot more extra controllers and stuff and they'd sell a lot more eShop games. Nintendo's potential future catering to core gamers aren't as bleak as you make it out to be Rol. If MS and Sony can run their business' like this, why couldn't Nintendo? They WERE making core games with N64, and had they continued to do so with GC (and been successful with it) they could have kept doing it.

One thing to keep in mind is that A LOT of people want Nintendo to go 3rd party or make mobile games. Why? Because there's a big market for Nintendo games, but they don't want to buy a brand new console to play them. Now, imagine these folks having tree choices of consoles; they have almost the same specs/power, they all have good 3rd party support and gets multiplats of most games, but only one of them have Nintendo games. That's quite easily a few more millions sold of Nintendo's console. Let's say 10m loyal fans, and then 10m more just because of their 1st party line up coupled with being just as good as the competition. That's 20m right there.

Man, that turned into rant didn't it?

why not both?
make mature games and childish too.
market the mature games for mature audience and chisldich games for childish audience.

Make a console that runs most of home console games, make it easy to port(unifyed arquitecure should help), so they can develop games for both handheld and home consoles(with a few exclusives in each platform), so they can bring a extensive library composed by mature and childish games.

they should keep investing in amiibo, or even faceplates. is a sucess, and both childern and aldults are into it.

Really hard to say, in the day's of the DS i knew several adults who owned one or atleast hade a shared one with their kids. Except one all of them have moved on to tablet mobile, or console/PC at home. Every 3DS that was bought was for kids. Looking at the Vita interest by adult consumers has al but dissappeared.

If i hade to make an estimate that in the West we are talking 10%, 20% tops of the 3DS buyers being adults. Japan is a different story offcourse.