All the leaks seem to have come to fruition.  The detachable controllers, the separate D-pad, the mobile/home console gimmick.  This leads me to think that maybe Nitnendo is hiding the rest of the patents/leaked information.  For instance the freeform screen and the supplemental computing device.  

I predict that there will be an entry level Switch and a Pro version of switch.  Why the divide?  Simple, because PS4 and Xbone have upgrades coming and VR being more important in the future.  Nintendo seems to be catching up with the times and a sign of that is with the Switch trailer itself.  In the trailer there were no kids, just a bunch of millinials, they had games that were not available on Nintendo.  Nintendo listened to all the backlash of the Wii U and has seen the trend with modern consoles.  Their answer to the times is a entry level Switch and a Pro level Switch that will include a supplemental computing device. 

Entry will be just the Switch console and the Pro version will include a supplemental computing device for the gamer who wants to more pixels in their games.  Because some gamers want it all, because some gamers will look at power as a selling point, because they can make these SCDs and cater to the ones that will fork over the cash.  Whatever reason, I really hope it happens because I want an option of a beefed up Nintendo Console along with the idea of taking it everywhere. 

So, is this even technically possible with their technology?

is it possible with technology, yes. SLI bridge plus GPU in base.

Judging how many 3DSssssss Nintendo have made...... I can see this happening.

I don't think it's possible to SLI without restarting the console or game.

Why have another GPU in the dock when you could just SLI with another NS instead?

USB 3 graphics cards are already being used. Thunderbolt connection on apple devices have been used for external GPUs for a while. It would make sense in the future for any device to be capable of high end graphics via a usb slot.

I don't think there will be a high powered model but I think Nintendo have left their options open for the future.

I literally just tweeted about this today in great detail and talked about it in another thread. My idea is different than your by a little bit, though.

I think the Switch is the first device. I think that eventually, they may release two other "sibling" devices at part of the same ecosystem. One called the Switch Pro, and one called the Switch Lite.

The Switch Pro is Nintendo's traditional console. What it essentially is is Nintendo selling the dock as a stand-alone unit. Instead of selling the dock with the Switch unit, all of the computational guts will be inside of the dock and it will be sold with a Switch Pro Controller instead. Because it doesn't have the tablet Switch unit, it will have a card slot built into the dock itself. So you just put your game cards into the Switch Pro, and play the games like a regular console. Because the Switch Pro still has a dock, owners of the original Switch can just dock their Switch's into the Switch Pro and have it function the same as a normal Switch dock would.

Then there is the Switch Lite, which is an undockable handheld Switch permanent buttons instead of Joy-Cons. It will be the size of a typical smart phone, and will predictably also have a card slot. Aside from that, I think you'll have a Switch XL and a Switch Lite XL (weird) which are just bigger versions of the those for people without baby hands.

All in all, I think that the Switch Pro will be their high end, the Switch will be their mid-tier and most popular, and the Switch Lite will be their low end. Their Mac Pro, MacBook/iPad, and iPhone respectively. There's also reason to believe they they will only make my Switch Lite idea, because they view the Switch as the high end, but my idea helps me sleep better at night so I'm sticking with it.

What's the point? It's not like they're going to catch the PS4P/Scorpio. They're better off concentrating on lowering the price.

For the vanilla Switch, I completely agree. For the future though, I think there is absolutely room for- wait you and I are thinking different things. Nevermind.

EDIT: Thinking about it for literally an extra second, I didn't even need to submit that post since the point is moot. Oh well.

I don't think so. It might be technically doable, but I doubt it's a magical solution to the supposed lack of power. It'll also probably be quite expensive. I also don't think Nintendo wants to segment the userbase like that right away. Besides, they've already stated the dock won't contain any extra processing power (I don't remember the exact words, but that's the impression I got). I think that's pretty conclusive and doesn't leave much room for adding extra processing power to the dock.

It's possible to make the dock as an external gpu, but it will be costly. I was hoping this happen to NS too but the rumor suggest something else.

Locked 720p for handheld and 1080p for console mode are good enuf for me

That's not what they said, though. What they said is this:

"The dock is not the main console unit of Nintendo Switch."

Which is true and obvious, and this:

"The main function of the Nintendo Switch Dock is to provide an output to the TV, as well as charging and providing power to the system."

Nothing about power, what the dock won't do, or what the dock will only do. Just the main function, which leaves room for secondary functions, like providing extra power when docked.