I could see that happening. The only issue is with the public statements NIntendo has made to shareholders where they actually spoke about brothers as part of an ecosystem in a family of hardware. There have only been rumors regarding the fusion concept or some type of hybrid console where as we many public statements referring to a console or the NX as a console exist. Your idea, while good, is really speculation where as what I have stated where you have 2 platforms, but they are not necessarily identical but still similar seems to fit in with actual public statements. This can also be backed up with actions when you consider how similar the wii u and 3ds are, their experimentation with crossbuy, and even buying one game that interacts with the other piece of hardware such as Mario Tipping Stars.
If we technically look at the actual quote from Iwata from Feb 2014:
Still, I am not sure if the form factor (the size and configuration of the hardware) will be integrated. In contrast, the number of form factors might increase. Currently, we can only provide two form factors because if we had three or four different architectures, we would face serious shortages of software on every platform. To cite a specific case, Apple is able to release smart devices with various form factors one after another because there is one way of programming adopted by all platforms. Apple has a common platform called iOS. Another example is Android. Though there are various models, Android does not face software shortages because there is one common way of programming on the Android platform that works with various models. The point is, Nintendo platforms should be like those two examples. Whether we will ultimately need just one device will be determined by what consumers demand in the future, and that is not something we know at the moment.
Sounds like it was still very much in the air as to whether Nintendo would have multiple SKUs (even more than two) or even just a few as a singular one.
Which direction they ultimately decided upon is a mystery to us right now. Maybe they decided to go the "brother hardware" route with multiple hardware SKUs, maybe they decided on one integrated SKU. This statement from Iwata doesn't discount either scenario.
Just based on the way the Unseen 64 guy, Reggie and Tanabe have spoken about it, I'm starting to lean more towards one integrated device.