If past history is anything to go by, Apple will lose. The UK does not and has never liked a company holding a monopoly over others. Granted it can take many many years before the country acts on a company but that is mostly due to the political climate at the time. What ever the arguments are for being right or wrong, companies that once had a monopoly were told to change. British Telecom (BT) once held a monopoly on the telephone system. They owned the physical cable lines, the phone exchanges and the sub boxes and no one else was allowed to use them. they were told to change and allow others to use their infrastructure. Now you have a multitude of different phone companies. It was the same with British Gas. They owned the complete system. They were told to allow other comapnies to use their infrastructure and now you have a multitude of gase companies. The Post Office was taken out of public hands, went private and was told to hand over some of it's business to competing companies because the Post Office had the monopoly on postal deliveries and thus it goes on and other with other businesses.
Anyone that tries to use Walmart in their comments are doing so for the wrong reasons. Walmart is a supermarket and as such there are many other supermarkets. Walmart is a dominant player in the supermarket business but the advantage is is that if consumers do not like the products or prices in Walmart, there are other supermarkets they can goto to get the same or alternative product. This is the same for many many companies and businesses that product services or products to the consumer.
This is not the case for Apples app store. There is only ONE app store and it is wholly controlled by Apple. There is no competing app store that consumers of ios devices can connect to. Therefore, if an ios app developer wants to get their app out to consumers, they only have one choice and that is Apple and they have no option but to abide by what ever Apples decides and sets the conditions to be. if they do not like the terms Apple offer, it's a case of tough luck, your out.
In todays consumer world, the consumer has choice over many products and services. A consumer has multiple choices on where they purchase a car, clothing, furniture, phone services, insurance services, repair and maintance services, food, utility services (not all and can be dependant on where the person lives), washers and dryers, music but if a consumer owns an ios device, they can only got to ONE place to purchase apps for that device and thats the Apple app store.
Many many years ago, if a car owner wanted to replace the lacklustre car radio in their car, they could only do so by buying a better model from the car makers authourised dealer and having it fitted by them. Consumer groups and independant businesses forced governent bodies to act and laws got changed. The same is now happening to Apple and also to Google with their Playstore.
Unless Apple has a legally compelling argument as to why they and only them are allowed to own and operate the ios app store, I have a feeling the UK and cases appearing in the EU will rule against them.