I'd like to think the final outcome is that developers can either "publish for a low/free cost and get charged 30%" or "pay a 'proper' fee, in the 100s of thousands, per year and pay no fee to Apple".

It's not an uncommon method, just look at game engines and dev kits that do the same, "small sale" companies, like less than 100k sales, can use it royalty free, where as others that use it for large incomes have to pay fees.