The optimal selling price for a game does to change becase developers add a fixed cost.
Suppose you have 1 Billion in fixed costs and 1$ in per unit cost and are given two options. The equation is just (number sold) * (unit price - unit costs) and that 1 Billion dollar fixed cost is irrelevant when maximizing profit (or minimizing loss).
What it would do is reduce the number of games created, as the industry becomes slightly less profitable. Which would then spread consumer spending over fewer titles and thus recuperate the burden of a union.