As for consoles, they ALWAYS had add ons. The famicom disk system. Satilaview. N64DD.
And if you want better performance, superfx and the n64 expansion pak.

4 GB models and 3 GBA models. They didn't make any GB revisions until 1996, though.

The Switch is designed so well though. I don't really see any significant changes for it. The Original DS and 3DS needed revisions at the time and so did the GBA. I just don't see any huge flaws that a Switch revision would fix.

I am on the camp of no major revision except for maybe memory upgrades. They might make a smaller more simple version of the Switch for kids though.

Imagine when tegra x2 or x3 becomes avaliable to fit in switch, it will be more efficient.
I dont believe in larger switch too. But maybe a larger screen, but with the same dock and joycon sizes, when better tecnology arives.
Also, a VR revision. (http://gamrconnect.vgchartz.com/thread.php?id=230827&page=1)
But the problem of a mini switch without detachable joycon and without a dock is that it wont be a 'switch'. The main feature of the console is changing to a mode to other, it is the name of the switch.
I can see a mini switch with and extra feature that you could switch between modes. Maybe a mobile mode, where you can play nintendo mobile games, or even a 2DS mode.
Or else, mini switch with detachable mini joycon. They can be expandable to became as the same size as the regular switch joycon. So, the same controller would work in any switch, despite their size. Also, it would also need extra tecnology.
Many things can happen.

But at least i can see a more efficient switch version, at the same size and form and better battery life. Id call it a revision.

I doubt we'll see a switch xl because it's already bigger than the Vita and the biggest 3ds by a good bit but a switch mini, switch pro and switch TV just make too much sense. A cheaper portable only version, a cheaper tv only version then a tegra x2 version to gradually phase out the day 1 model like the 3ds and new 3ds

A question, how much cheaper could a Switch TV be? No battery, no screen, no dockable parts... How much cheaper could it be compared to the regular model?

First of all, console upgrade and new version is a must on electronic Industries . To generate less onmanufacturing cost and increasing some profit , Nintendo like it or not, they will soon revising their internal chip.

Second , Nintendo need to keep a life cycle product, to keep the sales up, by renewing their product they will have a steady sales, so instead of releasing new consoles every year, they will instead renewing and make small modification , by re-branding and made some small improvement without loosing a big cost. 

Like it or not, if the new tech is coming , the old spare parts will not be produce anymore and it will be more expensive, then the new chips, so they will replace the old one with something better , cheaper, and smaller. 

In terms of tech perspective and Marketing perspective, hardware revision is a must or i could say a normal thing in Videogame Industries. 

If people get confused by joycon sizes, then they might as well buy a Wii U Pro Controller for the Switch and wonder why it doesn't work. And that wouldn't stop Nintendo either way.

Revisions will happen for multiple reasons. In a few years, there'll be more power/cost-efficient components for the system (screens, batteries, CPUs, GPUs), and there's no way Nintendo will ignore that. Heck, we already see it with Sony and MS home consoles constantly (PS4/3/2 slim, Xbox One S and whatever the 360 had).

I almost agree with OP, revisions are going to become less frequent with the Switch ...

Transistor technology progression is slowing down ... (less chances to upgrade the chips)
Big form factor ? (how much bigger does the Switch need to be ?)
Non-portable SKU ? (effectively kills one of the selling points of the platform)

eh.. I give this prediction a ~5% chance

there will very certainly be hardware revisions that change the APU die size/mainboard and probably affect battery size, pretty much every console that is seen as "success" had these (I'm unsure about N64 though)

but even if those "don't count" there is a very decent chance for a mini or handheld only Switch, as this could deal reduce prize and size, which both are suboptimal for a handheld and there is a good chunk of customers who'd buy it as a handheld/never use docked

wat ? we had 14/16nm node roll out in 2014, the 10nm node has gone live this year and 7nm is expected to hit in 2019/2020 - transistor tech has accelrated this gen