Steam will certainly remain software only. I think their long-term plan is to get a Steam footprint on consoles like they are doing with Portal 2 and they will work on expanding from there. If you want to see what happens to a successful software company that has a disasterous failure in consoles you look at Sega. Sorry Sega-Sammy Holdings Inc.

http://store.steampowered.com/hwsurvey

Judging by this, most of them do.