Oh shoot, yeah that may have been speculation based on that assumption. In which case it's probably wrong.
Per LiC, it appears the maximum speed of the DisplayPort interface isn't enough for 4K120, and as such it'll be maxing out at 4K60 output, which I think is reasonable. The thing is, the OLED Model dock, officially the "Nintendo Switch Dock with LAN Port", has features in line with this. It's a HDMI 2.0 device, with far more ventilation than OLED Model requires, and can, in theory, fit a thicker device than any extant Nintendo Switch model. Plus, unlike the previous dock:
It has an updatable firmware.
It nixes USB 3.0 ports.
That second one is interesting due to the firmware containing the following:
4kdp_preferred_over_usb30
(Per Switchbrew,
https://switchbrew.org/wiki/System_Settings )
The USB C standard on Nintendo Switch can support USB 3.0 speeds, or 4K, but not both. They don't have a reason to change this next gen given there's not much use for super speed USB ports on the dock. It isn't a PC, after all.
So it appears to be specifically designed with a future console in mind, at least from my perspective. Nintendo could change the dock, but with the Dock with LAN Port, they don't have to. Even if they don't use it, there's little reason it shouldn't be compatible.
As pointed out by
@SuperFakerBros - Nintendo has a history of reusing accessories, and with good reason. The Nintendo WiFi Network Adapter AC... adapter was used from its release all the way up until 2020, when New 2DS XL was discontinued. It's just cheaper and easier to reuse things if you can, from a supply perspective. Even the power consumption of NG Switch appears to be similar if not identical to the original Nintendo Switch based on the Nvidia data breach, so it could well reuse the AC adapter, and what is the dock if not a charging cradle, why not carry it over?
It also confers specific advantages, since it means they could produce just one Dock for both NG Switch and OLED Model, simplifying things even further compared to the current situation with two different docks.
I still believe in reusing the Dock with LAN Port- after all, they called it the Nintendo Switch Dock with LAN Port, not the Nintendo Switch - OLED Model Dock. If the next system still uses the Nintendo Switch brand and perhaps the logo with an addendum, why not use it?
Another thought is branding and aesthetics. See Dock with LAN Port is usually advertised in WHITE, but it also comes in black. What's so significant about that? Well, one, it means they can use the same dock and differentiate them in advertising by always advertising the previous gen in white, and next gen in black. Two, it means that they could take the dock with its extremely thin, moulded front panel, and just mould the Switch 2 logo into it, change nothing else, and have the perfect dock for NG Switch.
Personally, I think they'll just use the existing black dock to keep things simple, barring them changing the logo drastically next gen. The use of accessories in this manner is not unusual, the official Nintendo Switch (prior to Dock with LAN Port) and Wii U LAN adapter was the Wii LAN adapter, the GameCube Controller adapter is identical across Wii U and Switch minus a silkscreened logo. As mentioned, chargers have historically always crossed generations when it comes to Nintendo.
Nintendo tries to make designs to last, so as a final point, I find it hard to believe they'd design something for release in 2021 when they didn't need to, OLED Model could have used the original dock, with so many additional features, including HDMI 2.0 and additional air intakes, only to abandon it two, three years later.
