Also, consoles are specifically programmed for so that every drop of potential can be squeezed out of (very) ageing hardware. This doesn't happen for pcs.
Have to disagree. Consoles are locked in step with the generational advances, you're guaranteed that games will continue to be made for that console (assuming initial sales are a success etc) because the games are made solely for the console. But games for tyhe Steambox are also amde for the PC.
No more than consoles do, except they call it 'generations'.
Does the Steambox essentially self-obsolete then as newer games are released on Steam that it can't handle?
To clarify, imagine a Steambox released just before the jump to hardware acceleration. Within a couple of years everyone had stuck a Voodoo card in their machines and all the games being developed used 3DFX. The Steambox would be essentially dead.