Maybe in the future if Ninty completely does away with the LCD screens.

I 100% expect a Switch Lite OLED to appear and I have a feeling it'll appear in 2023. Nintendo claims the Switch is halfway through its lifecycle and Nintendo usually drops a new iteration of hardware every other year to keep the console fresh in the eyes of consumers, not just gamers since the Switch has really picked up on the casual crowd lol.

You had the launch Switch in 2017
Switch Lite in 2019
New iteration of the regular Switch with the OLED model in 2021
So history shows Nintendo could make a new iteration of the Lite in 2023 with an OLED model

It keeps costs low on Nintendo's end since they don't like to add horsepower to the Switch lol, and with how much praise the OLED model has gotten, it keeps the outdated hardware exciting again. Especially for those who prefer handheld. Huge profits for Nintendo, despite the outcry that it won't be a Switch Pro. Then again, Nintendo is gonna Nintendo lol

Lite is a low cost offering. I don't see them putting an OLED screen in.

I've been proven wrong with Nintendo and other corporations many times, but I really doubt it. While OLED tech is getting more affordable by the year (it was a big deal when the Vita had OLED back in 2011, and it was removed in the Slim revision for cost reasons), it's still notably more expensive than LCD. Nintendo really focuses on minimizing cost with their hardware (relatively speaking) and maximizing profits. It took them until the Switch to have a capacitive touchscreen. The Switch OLED only has a 720p display like the other models, they skimp out on internal storage, and the list goes on.
So why would they add a more expensive panel to the Switch Lite to chase yet another crowd that might not even exist? With how high Switch demand still is, I don't think they're going to get price cuts any time soon. Whether a Switch Lite OLED replaces or accompanies the Switch Lite, it would probably be $250. Switch Lite in 2021 is already overpriced at $200 (IMO) and Switch Lite would just increase that. It's clear that the hybrid Switch makes the big bucks, not the Lite.
Heck, I think we'd see Nintendo try a compact TV-only Switch before adding an OLED screen to the Lite.

Yeah, I don't think so. The point of the Switch Lite is to be a cheap product to produce in order to appeal to both parents or those looking for an extra Switch. Putting in an OLED screen there defeats that purpose, as the cost of OLED screens is higher than LCD.

The one caveat I will say is that if there is a Switch Pro release I could see Nintendo releasing a Switch with Pro-esque specs on an OLED screen. Similar to how they had the New 2DS XL near the end of the life for the 3DS. Had the spec upgrade, had the screen upgrade, but still pulled back on a major feature of the product (the 3D). That said, I do think that the point of a Switch Pro would be for modern TV displays not necessarily for portable play.

I doubt it. The market has shown that people consider Switch proper worth the extra price compared to the value of the Lite at its current price point. With Switch Lite appealing more to multi-Switch households or kids, lowering the price of that model to make it more desirable makes more sense than to invest in making it higher-end.

Personally, I see Switch Lite at $149 in 2023 - the same year I expect a Pokemon sequel to Sword/Shield.

Probably not, Lite is supposed to be the low cost alternative so I don’t think we will see an upgrade. But who knows, I never expected the New 2DS XL to be a thing either.

Japan would explode.

I would say Yes, changing just the panel is a low increase is the total production cost, so getting a new screen can help them to keep the $199 price tag for a few more months.

There's a small chance that we get a Switch Lite with HDMI output, is pretty easy for Nintendo to bring back to the motherboard the chip that makes a Switch capable of that.

I can see in one or two years something like this:

$299 - Switch OLED
$249 - Regular Switch
$199 - Switch Lite OLED (HDMI OUT please)
$149 - Regular Switch Lite

If the OLED is the equivalent of the New 3DS XL, then the Lite OLED would be the equivalent of the New 2DS XL, the last revision of the 3DS.

So yeah, I can see it happening