I think you’re think about the revenue functions for spot instances in isolation of the larger supply base of all instances. Spot instances are already a result of revenue management of a fixed supply base that increases in discrete increments over time. Instance capacity overall usually leads instance demand, shortage costs are very high in data centers.
Spot instance capacities are a function of the all instance capacity for the same type and on-demand instance usage. Spot instance pricing can influence the quantity demanded of on-demand instances of the same type, and vice-versa.
Anyhow, there’s no way we can figure out whether you’re right or wrong with any reasonable level of certainty.
While it's tough to say with certainty how much revenue is lost, there is certainly lost revenue. Consider that many substitute instances are available at the minimum allowable price (i.e., won't go any lower, there is unused capacity). These could be resold without moving the substitute market.
Spot instance capacities are a function of the all instance capacity for the same type and on-demand instance usage. Spot instance pricing can influence the quantity demanded of on-demand instances of the same type, and vice-versa.
Anyhow, there’s no way we can figure out whether you’re right or wrong with any reasonable level of certainty.