I think it's a little more complicated than that. I agree that developers are unlikely to lower prices if the 30% fee is eliminated or reduced. But it seems reasonably likely that the next time they look into raising prices, they may raise them less, or decide not to raise them at all.

I do agree with the underlying point: prices are not set based on cost, but are set in line with what the market will pay. If the market will pay $10 when the developer has to pay a 30% fee, the market will still pay $10 if that fee disappears.

But still, consider that for many apps there's going to be a tension between what the market will pay, and the minimum the developer needs to keep the lights on. The developer might settle for a lower per-sale profit if they get a bunch more users that more than offsets the lower per-user revenue.

Let's say a developer sells at a $10 price point, which nets the developer $7 (after Apple's 30% cut), and that they need $6 to keep paying their other costs; they'll get $1 in profit after all is said and done. But maybe they can only make 100,000 sales at that price point, or $100,000. Kill the 30% fee, and they make $4 per sale, or $400,000. Great! Instant 4x profit! But maybe they'll be able to make 150,000 sales if the price were $9, which would give them $450,000 in profit. That's a compelling reason to drop prices. Or at least not raise them even when their other costs go up from $6 to $7.

Obviously these numbers are made up; maybe dropping the price to $9 only nets them an additional 5,000 sales, so it's not worth it. But we can't just flat-out say that no developer will do the math and decide that dropping prices can actually help them.