Yet, there are M.2 and PCI express drives running at 2.5 GBs reads. Is up to Nintendo to choose the right tech. But Nintendo does like old and proven...

M.2 or PCI express cards are completely off the question for any console. They're incredibly more expensive than regular SSDs.

Is not about simply adopting a standar, but making a propietary one that could adopt a few tricks from them.

Even if this is 0.8TF as portable and achieving a boost to 1TF docked due upscaling, that would be able to support anything 3rd parties due. Personally I am expecting it to top out around 0.8TF docked, which is still great as far as I'm concerned but may be hard for the biggest 3rd party games.

Hard part is even Nvidia hasn't released hard details on the next chip and I am certain that is what Nintendo is basing their customization upon. All we have is speculation on that chip thus far. In fact, last data I found stated it only had one Denver core not two. Additionally, people like Emily have been very straightforward to not expect xbox1 power levels.

But that standard has to be economically viable.

Call me old school I remember when polygons were all the rage.  

It wasn't that long ago when Forza and GT were in a pissing contest over number of polygons per car.
Same with Lara's character model vs Nathan Drake, who has the most polygons!

Not everything about an M.2 drive is at a high prize. Actually, and I know you already know this, the M. 2 designation simply refers to the form factor. The reason why those drives are so expensive has to do with the type of memory tech used. The interface is flexible and can be used in different applications including some lower price ones. Thats because, as wikipedia, explains: "Computer bus interfaces provided through the M.2 connector are PCI Express 3.0 (up to four lanes), Serial ATA 3.0, and USB 3.0".

It obviously accomodates a wide range of options and posibilites. Definitely more flexible than the much older SD card standar.

It's more realistically probably 500 gigaflops portable mode, 750 gigaflops docked max. The Shield Console (500 gigaflops) still runs at a whopping 20 watts nearly when running a game ... that would kill even a monster sized battery in 1 1/2 hours and that 20 watts isn't even powering a 6-inch LCD display on top of that. 

To be getting even 3 hours of battery life the system cannot be consuming more than 10 watts/hour realistically. 

I also don't think Nintendo wants a situation where people "Switch" from TV to portable mode and all of the sudden the game starts to run like shit with an inconsistent frame rate and downgraded graphical assets. People who aren't tech savvy are not going to understand what's happening and in some cases may think something is wrong with their system. 

I don't think Nintendo really cares about PS4/XB1 power or even having that many ports either. As long as a few of their Japanese developer buddies support it anything else is gravy for Nintendo. They're getting Dragon Quest and some version of Monster Hunter almost certainly, that alone in Nintendo's mind is probably 70% already of what constitutes good support.

But SD cartridges and slots are mass produced, and therefore are cheap. What you describe would be made only for Nintendo, and that low production would make it a lot more expensive.

Don't get me wrong, it would be great if Nintendo or anyone else used something like that, but between not having actual need for them right now and the cost it would have, no one will go that route.