Even more than giving the operating system a fresh coat of paint, making iOS more flexible will be key in keeping it competitive. That’s an issue that Cook acknowledged last night, with some caveats.

“On the general topic of opening up APIs,” said Cook, “I think you’ll see us open up more in the future, but not to the degree that we put the customer at risk of having a bad experience. There’s always a fine line to walk there—or maybe not so fine in some cases.”

“We think that the customer pays us to make certain choices on their behalf,” he continued. While some may want to dive into multiple settings screens to tweak their phones to be just the way they want them, Cook doesn’t see this as a welcome feature for mainstream customers. “But, will we open up more? Yes.”

Cook didn’t say specifically what this “opening up” would entail, exactly, but it does seem like hopeful news for the people who only jailbreak because they would like to set Google Maps or Mailbox to be their defaults.

If I had to guess, I’d say the changes will fall somewhere between the inflexibility of iOS as it is now and the extreme, fundamentally experience-altering flexibility of Android. It seems likely that third-party applications will be able to integrate more deeply into the operating system, replacing the defaults and sharing information more freely, but it seems unlikely that Apple would allow third-parties to replace anything as fundamental as the application launcher or even the keyboard.

This is all just speculation, of course, but it’s all done with Cook’s “fine line” in mind. Apple will still want the experience of using any iPhone or iPad to be fundamentally similar across devices (thus avoiding the fragmentation of experience that Apple execs have railed against in the past), but allowing users to open links with Chrome by default instead of Safari shouldn’t do much to upset this balance.

This is all so much tea-leaf reading until the notoriously secretive Apple actually gets up on stage and starts making official announcements, of course. Our own Jacqui Cheng will be on the floor at WWDC covering Cook’s keynote, and with any luck Cook will be just a little more open about the future of the platform.