TL;DR: Antec is going to be selling a Steam Deck competitive device, based on the Ayaneo Slide. The device has a slide up screen that reveals a keyboard, which is good because using desktop windows is much easier with a keyboard. However the device’s lowest estimated power draw at low/no load is 15w, meaning it will use comparable power to the deck running at max power. This means the battery life will probably be pretty rough when compared to the Deck. It will also likely have a much higher price point.
Maybe you could, but the whole point of the steam deck is the ability to play any PC game, and most require mouse input to play well. Most people would be unwilling to make that tradeoff
That depends on what they bought the Deck for. Not everyone has much of an interest in playing games that require the trackpads, so there’s still a big market for handhelds that cover the rest.