In the leaked info, we know that Valve has an upcoming device that will use the same APU as the current Steam Deck. We don't know if this will be a new VR headset or a Steam Deck hardware refresh. Even though using the same APU means there won't be a performance increase, there could be various other improvements in an upgraded Deck like a better screen, etc. What would you like to see in a partial hardware upgrade?
You can sorta already use the deck as a controller iirc. You can stream a game to your deck and still have it display on your PC. Just turn your deck screen brightness down and play.