I'm really glad to see that these new consoles will continue to have ethernet ports. My whole tv cabinet is full of devices that need networking and its nice to keep as many devices as possible on ethernet and off the wifi network.
I think for gaming oriented devices this trend will continue for some time. _maybe_ with exception of some nintendo consoles which are more casual.
That being said.. I am gaming on wifi regularly and have no in-game issues related to it (low ping, stable connection, same room as the router, 5Ghz band only used by the machine on which I game + work machine, but those don't happen at the same time).
I think you'll see it on anything that someone wants to do "cloud gaming" on, by which I mean, the full "run the GPU in the cloud and stream the video back" thing.
I've used Steam Link on a computer in my living room running Wifi to the internal router that runs a wire to the receiving TV. My wifi is one of those dedicated mesh router things that is as solid as you can buy. And it mostly works... but still has occasional jank and even more occasional bad days where it never stops working but noticeably drops resolution a lot.
It's just too easy for an otherwise functional home Wiki connection on its own to eat all the latency budget or more for that style of gaming. And the companies really want you locked into more subscriptions, not owning your games, and streaming everything if at all possible, so I'm sure they'll continue building the hardware for it. Ethernet is cheap; not so cheap you can't save a lot of money over several million consoles, but so cheap that it's a no-brainer for this purpose; retaining one marginal customer on the cloud service that works on ethernet but not on their wifi pays for hundreds of ethernet ports, if not thousands.
I couldn't handle Steam Link on WiFi. For anything beyond Stardew Valley and Rimworld the sudden quality drops and latency were too jarring. After setting up an additional gigabit switch for the bedroom and running some Cat5e it works well enough for most FPSs.
For games that require low latency, such as twitch shooters and (traditional) fighting games, a wired connection is indispensable. I don't think the "hardcore" platforms will ever remove it.
Regarding Nintendo, while they've never shipped a console with an Ethernet port built-in, they have supported it since the GameCube (Broadband Adapter); the Wii, Wii U, and Switch all accept standard USB Ethernet dongles. Use of these adapters is somewhat widespread on the Switch, particularly for Mario Maker and Smash (although this is more due to Nintendo's incompetency with netcode than inherent latency in Wi-Fi).
It's absolutely for the latency, it's almost a faux pas to play the games I mentioned online at a high level without an Ethernet adapter (since there's a decent chance you'll get a match with others who are). Additionally, the Switch is the sole major gaming platform which has avoided the bloat endemic everywhere else; there are no games on the platform anywhere even close to triple-digit GBs in size, or even half that.
>I'm really glad to see that these new consoles will continue to have ethernet ports
I expect mainline consoles will have a hardwire option (ethernet or otherwise) forever. There are game genres (like fighting games) that are latency sensitive and it would kill the competitive scene for that console if Wifi was the only option available.
For me, it's less about the latency, and more about reducing congestion for other devices that don't have other options (i.e. mobile devices). My laptop docking station is cabled too for this reason.