I agree. After all, they are still selling it, and people are still happily buying it. A friend got one about 3 months ago and he's been very pleased.
The Steam Deck is still under four years old, let's remember. The Nintendo Switch is over eight! Of course that's not an apples-to-oranges comparison as the Steam Deck aims to run any game, not just specifically optomised titles. But it's an indicator.
On the subject of being old, we get way more life out of PC hardware right now than we did back in the early 2000s. Nowadays if you buy a high end GPU you might get a decade of gaming out of it. Back then you'd get 2-3 years and it would be obsolete, because graphics tech was just evolving so fast. (Of course, cards now cost ten times what they did back then, but that's another story....)
Point is, there's plenty of life left in the steam deck yet :)
Ah. I suppose it's just down to how my client chooses to handle it, then :)