The only way Nintendo will get exclusive hardcore games is if they make them themselves, or have one of their 2nd parties like Retro do it.
Exactly. Third parties don't really make exclusives that much anymore. And if Nintendo is just throwing out Wii Series junk and expecting the third parties to handle the core part, they're only going to sell to Wii owners who never bought a second console.
The problem is Nintendo has moved more and more into sticking with their existing IP. They take talented devs like Retro and stick them entirely with sequels to existing Nintendo IP. So we don't get anything new and if Mario, Metroid and Zelda doesn't sell someone on the Wii U, they won't buy it because there won't be anything else. Nintendo's current practices prohibit anything new attracting core gamers because they never make anything new for core gamers. We'll never get an exclusive Nintendo FPS unless they shoehorn some existing Nintendo IP into it.
There are a lot of factors at play and a lot of things that need to be considered. I don't think Nintendo realizes that judging by what they showed at E3. There is a huge difference between starting a new generation at the same time as everyone else where every customer is considering buying a new system. The goal is to get them to pick yours. But in this case the competition's userbases don't NEED to buy a new system because those systems are still current. They have to get them to SWITCH which is WAY harder.
I am not trying to distract from your overall point. Yes, Nintendo does stick to it's existing IP's instead of making new ones. However, you fail to mention the other publishers that do that. So I will make a list for you:
EA: Madden, Sims, Battlefield, Need for Speed.
Capcom: Devil May Cry and Resident Evil
Microsoft: Halo
Square Enix: Final Fantasy
However, I have to admit that Nintendo is more guilty then the other companies. The best publisher is probably Ubisoft. They have made more new titles and continued with their franchises. But that still does not negate from the fact that Nintendo is not the only one who sticks to it's original IP's.
Of course, not many publishers have such a huge line up of top selling IP's. You named a few, Zelda, Mario and Metroid. However you have Kirby, Kid Icuris, Super Smash Bros, Star Fox, F-Zero, Metal Combat, Donkey Kong, Earth Bound, Fire Emblem, Ice Climber, and I am sure I am missing some still. The good thing is, giving Metroid to Retro was the best thing Nintendo has ever done. And letting them have some fun with Donkey Kong was also a good idea. It was a game that was old and almost forgotten, and then bam Nintendo revived it.
So yes, they need to make some new IP's (not like they haven't -- Animal Crossing and Pikman are both newer IP's) but I would like to see some older games on Wii U. Star Fox for instance.