I doubt it. Far too many people want games on release. I think most of sales during these sales go toward people who didn't want the games that badly in the first place. For instance, I wanted to play The Incredible Adventures of Van Helsing, but I didn't want to play it badly enough to pay $15 on it. Not much, sure, but I still didn't feel like paying for it. On the other hand, I bought Black Flag on release. $5 seemed like too good of a deal to pass up on a game I had been keeping my eye on, however (Van Helsing).
I'd guess a lot of people who buy games regularly do the same thing. Important games at full price today, less important games later when Steam makes me an offer I can't refuse...