I would argue the only fees that should be based on revenue are payment processor fees, and maybe distribution/CDN costs (althouth these should be instead charg

I would argue the only fees that should be based on revenue are payment processor fees, and maybe distribution/CDN costs (althouth these should be instead charged per byte carried). And even then, these are astronomically low compared to the current 15%/30% cut. Everything else is paid for already by the end user of the device (who consciously pay a premium to use Apple's ecosystem), and has no reason to scale linearly with developer revenue.