SteamBoy won’t be as powerful as other announced Steam Machines in the same way [the] Nintendo 3DS or PS Vita performance is not comparable to Wii U or PlayStation 4,” … “However, it will be possible to play the majority of current games in Steam.” – Representative of Steam to The Escapist
It looks as though Steam will be giving a handheld model that may not be able to be able to run every game on every platform. But the nostalgia value of steam with older games and RPGs along with new games, possibly like Hearthstone will not now be at the availability of your fingertips.
The beauty, and general function, is to make all Steam games mobile. With all of their amazing sales and diversity of PC games available on Steam, the SteamBoy will be something to look forward to in 2015.