Switch Mini/Pocket. We will not have handheld that will completely new or different platform.

I would made a hybrid, that could be played as a home console or a handheld... Maybe with detachable controllers.

Yes...

They might call it Switch Mini or Switch Go...

(I have just reelazied that pretty much all of you have said the same -  ther eit goes my contribution to the world)

a new handheld only hardware will be released...

However I might think Software will be a shared experience!

Still a hybrid, but a different one:

A switch phone with 5-5.5 inch display. To make it thin enough it will loose the ability to read cartridges, so it's going to be digital only, and the Joycons are non-removable and actually part of the case. On the plus side, it adds some productivity apps to Nintendos game library and of course complete phone functionality. And it comes with an audio jack for headsets.

To reduce the power consumption it will come with an evolution of Tegra, but clocked down to match more or less original Switch performance, and clocked down even further outside gaming so it will last for a whole day at least when not gaming all the time.

And I expect it to come out around 2020 at the earliest, after they came with an XL/LL and an upgraded Switch. So basically the Switch Phone would be analogue to a 2DS in the 3DS lineup.

As some have said, Switch.

However, I would like a Switch Home or Pro where it's a dedicated home console only. Tegra X3 based, all games run 1080p60.

That way, Switch platform is both successor to 3DS (tablet console, and of course doubles as home console) and WiiU (home box).

Not sure why the thread didn't just end with this post.  It's the most accurate and obvious answer to the proposition by the OP.

The OP assumes there doesn't need to be a successor.  Personally, I don't play a 3DS or want one.  I owned a DS and barely played it.  I've just never been that much of a portable player.  I was just curious what the 3DS owners thought.  Are they happy with the Switch being the successor (they seem to be!) or are there things they would want Nintendo to implement that aren't in the Switch or the current 3DS.  I've loved the mockups of future iterations of the Switch in here.  I think it also makes sense going forward for them to just make more portable revisions of the Switch, especially for their software output.  It would seem as the Switch is the end of a disk-based experiment for Nintendo, so to is it the end of their dedication to a two screen platform.

This one looks cool.

oh... right....
The 3ds already has a successor, it´s the Switch !

As a 3DS and Wii U owner I am very happy with the Switch being the successor for both.  The tech has been available for Nintendo to combine their handheld and console offerings for a while now and it is great to see them finally doing so.  I know Nintendo has gone out of their way to state that the Switch isn't the successor to the 3DS, but I feel like that is more just because there technically won't be a successor to it.