They don’t have the means to produce at scale, which has resulted in wild price fluctuations on their end. (even though to steamdeck OLED did sell out at the much higher price.) To me at most they will continue with the controller, but that’s about it.
I have never gotten a Steam Hardware product directly from steam, always used. Even now I can get a used OLED Steam Deck 512GB for about 450€ in very good condition in my area. That’s the thing about their Hardware is, that they are usually novelty products that people will always have a good reason to keep or resell. The fact that they can’t keep up with production doesn’t mean you can’t have their products. Steam sells them and gets their share of profits anyway, so it doesn’t really matter how you get yours, as long as they keep cleaning out their stock.