I don't think the next big thing will be hardware. I think the only obvious "big thing" on anyone's horizon is just much more IoT interconnectivity, smarter, more connected smart assistants, and more smart automation.
Picture your alarm waking you up, the lights in your house gradually brighten, the coffee maker in the kitchen automatically begins brewing a cup, the display on your smart fridge is playing the morning news while you prepare lunch to take to work. You're on your last stick of butter, so your fridge orders more, set to arrive when you get home from work. A commercial for McDonalds comes on TV and your phone lets you know that if you stop at the McDonalds on your route to work this morning, McDonalds will offer you a personalized coupon for your favorite breakfast items. Because your phone knows what you're watching on TV, knows what you like, knows your route to work, and can negotiate these sorts of promotions with retailers based on your preferences. Your car automatically warms up and adjusts the climate control to your desired settings, and GPS plots the best route to work before you even sit in the car... your car practically drives it self to work. Your McDonalds order is placed automatically as you approach and your approximate arrival time is communicated to McDonalds, you simply wave your phone by a keypad in the drive thru to confirm your arrival and payment and your food is ready and waiting.
Some automation and interconnectivity like this is already available in some capacity, but the first company to deploy on a larger scale and further refined... where it all works seamlessly behind the scenes. Baked in to the OS rather than a collection of 3rd party apps and services. That is where we are headed. Apple could be that company. Siri. Continuity between iOS and OS X devices, Apple CarPlay, Apple TV, the rumored Apple autonomous car... HomeKit. The dots are there. They just need to be connected on a massive scale and refined. All of these devices and more, actively working together to automate your entire life.