Now for the main reason why N+C cannot match the lifetime sales of its predecessor. It's a question of content, but not in the sense of levels or amount of things to do. The Nintendogs IP has no central character nor a unique world (like Mario or Zelda games), so it's much easier for competitors to take sales away. There has been an abundance of pet simulators on the DS and other devices in the last few years. Not as good as the original, but cheaper. Nintendogs is still a good brandname, but the series cannot protect itself from copycats like other Nintendo IPs. Other companies can make dogs and cats games, but they cannot make Mario and Zelda games. I hope that this explains this point well enough.
Brain Training will be hit even harder, so Nintendo cannot seriously continue it on the 3DS. They will have to come up with a new brainteasing experience. Whether that is some new logic puzzle or a well-designed package, I don't know. But it cannot be More More Brain Training. The IP is kinda useless now, just like Tetris's hardware selling power greatly diminished over time, because it was put on pretty much every device. But this kind of stuff will always work for a single generation due to the first mover advantage where the market associates one type of game with a specific gaming machine.
OK for almost everything here, I enjoyed reading this part. I am not sure Nintendogs is entirely replaceable due to the quality of Nintendo's offering of the game. You touched on this a bit, but I would be hard pressed to see Nintendogs be pushed out by the copy-cats simply due to the quality of what Nintendo offers in it. I know you don't like when I do this, but it's a game sales site, so bear with it.
This list contains most of the items with dog, dogz, dogs in it on DS, including Ubisoft and Square-Enix's offerings. Nintendogs has captured a market the others don't even touch the foot of. The total of said games is 28.58Mil, Nintendogs takes up 24.36Mil so clones get 4.20Mil. The 3DS version holds another 2.1Mil. There is still another 20Mil (24 NDogs - 4 Clones) to reach.
Who did Nintendo attract with that game, they are out there somewhere. Nintendo tapped into a market the clones can only dream of at 25Mil sales. There is still that market out there.
This same logic applies to Brain age and others. I didn't even realize this until preparing my reply. At first I was agreeing with you. Seems a little counter-intuitive, but it's surprising to be true.
Super Mario Bros. is THE Nintendo core game, especially after its sales performance on the DS has proven once again that it is. What you call "Nintendo-core" could easily be considered Nintendo catering to their Nintendo 64 fanbase. That isn't Nintendo's entire core costumer base though, rather it only represents the games that Miyamoto personally wishes to make. And honestly, a lineup that looks like the Gamecube's is very bad, because we know how the Gamecube sold. Coincidently, the 3DS tanked and still isn't completely in the safe zone.
Honestly, from a business perspective it made no sense whatsoever to hold back a sequel to NSMB for such a long time. Nintendo is usually a very well-run business, so the most plausible explanation is selfishness on Miyamoto's part. He has a lot of power and freedom and he doesn't want to make another Super Mario Bros. It adds up. Sure, there's nothing to prove this with 100 % certainty, but all other theories boil down to Nintendo's businessmen suddenly suffering from severe brain damage.
By "Super Mario Bros.", you mean 2D SMB as in NSMB I understand. I like the distinction you make with the N64 base. True, that is what I considered the Nintendo core. I understand these people buy NSMB (as I did) and thoroughly enjoyed it, but we also bought SM3DL. The big question is, who was Nintendo aiming? If they were aiming us, why didn't they just release NSMB as you suggest?
I believe it is for a question of image. Nintendo wanted to avoid emitting the image of offering an overly casual console. Yes, Resort and N+C, but I believe they wanted to keep it mild. So, to cater to the core and attempt at a core image, they held off on the Core+Casual appealing NSMB. Add to this that they probably wanted to keep SMB for year 2 to 3 of the 3DS as they did for DS and Wii, so as to ensure momentum in the peak years. It's a game of "Keep hitting" if you know what I mean. With these two reasons, that's how I figure it.
That is why I understand they didn't give SMB at launch. At the same time, they didn't want to reduce the sales numbers to 3D levels and they also wanted us to feel the stereo-3D effect, so a 2D-3D hybrid became their solution. Lastly, they brought the NSMB themes to the 3D offering (as we all know SM3DL looks and sounds alot like NSMB) so as to bolster appeal. All in all, I don't think it is Miyamoto's decision, I believe it was a team decision. Iwata, Miyamoto and all stakeholders seem to have a hand in this.
This is the explanation I understand. As for LM and the list you offered, again, they want to hold an image for now, keeping casual to a mild level. Iwata went on record about this, but I lost the quote. He said something around the lines of they are focusing first on core, and working at keeping a fragile balance between casual and core for the 3DS. I understand this to mean that they will bring in the casual games, but for the start, they don't want to scare away some core that are less familiar with Nintendo. It doesn't mean they put all casual aside, but they are keeping it dosed.
I don't think it's all about Miyamoto honestly. I see alot of Iwata in this.