It depends on how the program works. If SteamOS works like Android then yeah we might be cooked on the hardware support. If SteamOS works like a normal linux distro/OS we'll get more support.

In practice this is a good thing because most of the parts of SteamOS are open source, meaning that as long as you don't have a device with a locked bootloader you'd be able to run comparable OS simply using all the software that's bundled in Steam OS.