I've gotta say, I've been hearing these "Switch Pro" rumors for about 3 years now, but this is the first one that actually sounds credible.
“The OLED panel will consume less battery, offer higher contrast and possibly faster response time when compared to the Switch’s current liquid-crystal display,” said Yoshio Tamura, co-founder of display consultancy DSCC.
That part sounds totally believable. This looks like a cheap way to get improved graphics and more battery. That is the sort of thing Nintendo usually looks for. On the other hand, when it comes to 4K I wouldn't expect much. The XB1 S can stream 4K, but it's still less powerful than the base PS4. I think the main graphical upgrade we are going to see is going to come from the OLED screen. This new model will probably get a minor processor upgrade like the 3DS, but not a major one like the mid gen upgrades of PS4/XB1.
So, I think this article is true as long as you don't get your hopes up about the 4k. I can actually believe Nintendo will have an upgraded model sometime this year, because 2021 is about the right time for it. I can also believe it will have an OLED screen and a longer battery life and maybe a small upgrade to the processor like the New 3DS did. This upgrade is going to resemble the New 3DS upgrade a lot more than it resembles the XBox 1 X upgrade.