Yes, the revenue per sale has declined by a third. But if the number of sales double or treble in the next 12 months, does anyone really care?
You need to stop viewing this as a revenue discussion vs. a profitability discussion. Let's use some concrete numbers instead of abstracts...
You own a company that acts as a distributor of content. Since the inception of your company you have held contracts with the content owners that allow your company to keep 30% of the sales price and the remaining 70% is provided to the content owners. Let's say that you are selling content item A for $100. For each sale of A you receive $30 of revenue and provide $70 of revenue to the content owner. Let's assume that you had to pay $10,000 (+$99 developer fee) to develop your iOS application. Hosting/bandwidth fees for that content item is $0.10 per download (assumes that you have many other content items to spread these fees across). Visa/MC/Paypal charge you 3% for payment processing. Finally let's assume you have 100 downloads of A per month.
Payment processing per download is $3 (3% of sales price). With a revenue stream of $26.90 per download, you would need to sell 376 downloads before you break even on your initial costs (just under 4 months). For simplicity, let's say that you are a one person company and only have to pay your salary. After the first 376 downloads, every other download nets you $26.90 which can be reinvested into new apps or paid out as a salary.
Let's add in the 30% IAP fee...
Apple charges you $30 per download. The content owners are owed $70 per download per contract. The payment processing fee goes away as Apple is handling that for you. Since your company is still hosting the content, you still need to pay the $0.10 per download.
Here you can see the problem. You have invested $10,099 in upfront costs for your app development. And you are hit with a recurring expense of $0.10. Increased sales will only hurt you more.
The only path for your company is to renegotiate your contracts with the content providers or leave the iOS store. Then the question becomes, why would the content providers renegotiate their contracts with you, when they can work directly with Apple and sell through iBooks etc and continue making the same revenue per download (70% of the sales price)?
The drawback to this relationship is that the content purchased through Apple can only be used on iOS devices. Your company can continue to work with the content owners on other platforms as the 10% fee paid to other marketplaces, while it reduces your profit per download, it still does not eradicate your profitability.
This is the type of issue that apps like the Kindle and Netflix could face. Is it dependent on how the terms are written in the contracts with the content owners. This example uses sales price. Other examples could be based on distributor revenue (as you hinted at) and others can be based on a flat fee.
All I know is that if your model was based on a percentage of sales price you got screwed as 30% is a pretty standard rate. If you have a flat fee contract type, you likely got screwed (but it depends on if the flat fee happens to be less than the 70% of what you can actually sell the content for). If you are a revenue type (the least likely as the content owners would have to accept that they are selling there content for variable rates), then you are not affected.
This is the dilemma.
GL