Whatever cat Apple names the next Mac OS X update after, it's a sure bet that OS X 10.9 will continue its trend of iOS feature integration. Lion and Mountain Lion carried over functionality like LaunchPad and Notification Center. According to 9to5Mac, 10.9 will integrate Siri and Maps into the operating system.
The site reports that Siri is in testing for the next version of the operating system, which isn't a guarantee it'll survive for the final release. But the move makes sense for Apple: Siri has name recognition and could potentially replace an existing feature like OS X's Dictation while adding extra features like returning baseball scores and referencing science fiction movies.
While Siri only supports certain iOS devices (the iPhone 4 and iPad 2 were left out in the cold), presumably the last several years of Mac computers would offer ample processing power to handle Siri. Of course, there's no guarantee--but if a system can handle the next version of OS X, it can probably support Siri's natural language recognition.
9to5Mac indicates that Map support for OS X will allow developers to embed maps into Mac apps. It's unknown whether Apple will offer a standalone map application for the platform as well.
Some of the features Apple has carried over from iOS to OS X, like LaunchPad, seem stuck in the design language of touch. Big icons are great for mobile screens but less necessary on laptops and desktops with more precise mouse pointers. Siri and Maps will work just fine with a mouse, but if Apple does continue to borrow iOS elements for OS X, are touchscreen laptops an inevitability?
Windows 8 has faced its share of criticism with the launch of the Surface RT, but the implementation of touch itself has been well-received. Touchscreen laptops still have some quirks to work out--for example, the screen must be rigid enough to resist bouncing back and forth with every touch input--but that's the kind of engineering Apple typically excels at. High resolution "retina" displays are clearly a priority for the company now, but touch seems like an inevitable step for devices introducing more and more mobile features.