IDKFA
I am Become Bilbo Baggins
I don't see how this thing is going to be successful when it's not even coming to retailers. The mainstream audience and the casual gaming crowd that they're targeting aren't going to go look up a steam machine and buy it directly from valve because they're not going to know to do so nor know wtf it is. This thing just has bomb written all over it from the tech specs to the mysterious price to the concept of it.
Like the Steamdeck, this is a niche product. Valve aren't targeting 100 million sold.
Multiple millions sold would be a success. Success for Valve might also be judged by how well it drives software/games sales and how much it expands the Steam user base.
They're not aiming for PlayStation or Switch numbers.