You know, this could actually be a good thing. Steam already has the road paved for reselling with its inventory system. They just haven't used it for that because other publishers and devs will scream bloody murder if Steam allows the return of that evil demon secondary market. If somebody forces their hand, they'll figure out a good system for this; if anyone can do it, it's gaben. Many companies will jump ship, possibly going as far as to yank their titles and cause some kind of... refund cascade failure. But Valve will easily survive it and become better for it, and fuck anybody that reacts in that fashion in any case.