As in artificial intelligence. And I'm not just talking about giving Siri an even more dazzling personality. I'm talking about robots. Androids. Sorry, I don't mean Google's mobile OS.
See, this is where the future OS is at. Not OS XI or iOS 7 or 8 but a totally revolutionary OS that is intelligent all around.
Something like Siri 5.0. One that can carry along a more natural conversation and truly act as a personal assistant.
Eventually, it could be Apple's AI that power our homes and lives.
That's where I would put a few billions.