Doubtful will help the consumer at all. Why cut the price where the developer can pocket the money Apple use to get?
Developers could drop their prices by 30% (or 15% depending on size) and lose no revenue while at the same time attracting new customers.
Where would savings for developers or customers - whoever those supposed savings would effectively fall to - come from? If Apple is eventually forced to allow third-party payments for IAP as a result of this ruling, it will likely require commission payments on such sales high enough to negate any supposed net savings.
There's an aspect of how antitrust law works, as relates to this situation, that I think many don't fully appreciate. Apple has a legal monopoly when it comes to the use and control of its intellectual property. It has the right to charge what it wants in exchange for allowing others to use that intellectual property. Apple could set the commission rate (for sales made through apps using its IP) at 30% or 50% or 70%.
However, what could cause antitrust problems for Apple is tying its legal monopoly on control of its IP to other things which it doesn't have a legal right to monopolize. So it might have problems if it tried to use its control over the use of its IP to maintain dominance when it came to, e.g., IAP payment collection or processing. One way it might do that is to underprice its payment processing services (in connection with the licensing of its IP) so as to give it an unfair advantage over other payment processing services. It might, e.g., charge a 30% commission on IAP it doesn't handle itself and also charge a 30% commission for IAP it does handle itself. That could be seen as anticompetitive behavior that lacked procompetitive justification. It might be seen as illegal tying - an illegally anticompetitive attempt to effectively force developers to use its own payment processing services.
This is where some of the arguments that have been made against Apple's 30% commission rate actually help Apple, and I suspect many who have made those arguments don't realize it. The argument that others could provide payment processing services at a much lower rate - for, e.g., just 5% - would help Apple justify charging a higher commission rate - of, e.g., 25% - for IAP it didn't handle itself. Others actually providing such services at lower rates (if this ruling eventually goes into effect) would even more so help Apple justify charging higher commission rates. It would mean that Apple wasn't effectively charging those who chose to use its own payment processing services an unfairly low - an anticompetitive - rate for those services.
Further, Apple might be able to justify an even higher commission rate for IAP it doesn't handle itself relative to the rate it charges for IAP it does handle itself (e.g., it might be able to justify charging 30% in both cases) based on certain procompetitive reasons for doing so. For one thing, collecting its commission on IAP that it doesn't handle would be more difficult and less reliable. It would be easier to collect that commission from developers who use Apple's payment processing. So Apple might be able to justify, e.g., charging those developers an effectively discounted rate for everything other that payment processing - e.g., 25% instead of the 30% it charges developers who don't use Apple's payment processing services - which offset what it effectively charged them - e.g., 5% - for using Apple's payment processing services. Under current antitrust law, procompetitive reasons can justify what would otherwise be anticompetitive behavior.
At a minimum I think Apple can - without antitrust problems - justify charging developers who use third-party payment processing the difference between what it charges developers when using its own payment processing and what others charge for payment processing. So, e.g., if it charges developers 30% on IAP it handles and other payment processors charge 5% to handle IAP, Apple could justify charging developers 25% when they use other payment processors.
More generally, when it comes to potential changes that might open up the iOS platform (for, e.g, third-party payment processing or side-loading of iOS apps), the more the issue of Apple charging a commission for the use of its IP is untethered from other issues (such as it charging for payment processing or hosting of apps) the more Apple is freed up to charge whatever it wants for the use of its IP without creating antitrust concerns. It's the tying which could, under existing antitrust law, cause problems.