At WWDC the announcement of OS X Mavericks, plus the release of the new Intel Haswell-based Macs on which it will eventually run, reaffirmed Apple's direction to keep touch with the province of iOS devices. Meanwhile, on the Windows side, we are increasingly seeing a host of ultraportables that can either convert to a tablet by rotating or twisting the keyboard or have the touch-enabled screen detach for a purer tablet experience.
While we've seen a number of Windows makers enable this on PCs that are 13" or even larger, it makes the most sense on smallest notebooks since those make for a more comfortable tablet scenario. If the trend keeps up, the 11" MacBook Air may be the last notebook standing (or, rather, poised on a surface) that doesn't have some ready-to-manipulate touch display. There needs to be good reasons for going against such a grain, and in Apple's case, there are.
Tim Cook was addressing the Windows 8 user experience when he referred to the convergence of a toaster and refrigerator as an unsatisfying product. The dichotomy that Microsoft has created with Windows 8 and RT has resulted in a fractured experience for the former and an app shortage on the latter. A MacBook-iPad combination interface likely would not be quite as disjointed as Microsoft took great pains to differentiate its "Modern" UI from the iPad and thus the Mac, but clearly there would be fundamental challenges to resolve such as the use of windows and menus.
Meanwhile, the iPad has had no problem attracting apps. Sure, many those apps may not offer the depth of features that OS X apps at this time (Apple's own iWork and iLife apps are examples of that.) but there's no need to prop up the new platform with apps from the old as Microsoft has done.
Indeed, third parties have offered a wide choice of keyboard options for the iPad including standalone full-sized and portable keyboards, cases with integrated keyboards, ultra-thin covers from Logitech and Belkin, and laptop-style docks such as the Brydge. True, these all rely on Bluetooth and therefore require their own batteries unlike Microsoft's Surface keyboards or certain Windows 8 tablet keyboards that can charge the PC while it is docked.
The iPad is a new beginning. The Mac isn't going anywhere anytime soon. In fact, in announcing OS X Mavericks, the company intimated that it plans to have OS X around for another ten years. However, one must face certain advantages that iOS has. It powers Apple's smartphones, key to market share as the largest device category in the world. It runs on Apple's processors, which use the ARM architecture that provides efficient horsepower and where Apple can customize the specifications of its own chips. It enables thinner, more portable, and less expensive devices. The iPad also has a much shorter learning curve than the Mac and largely dispenses with inhibitors such as knowing how to type and hierarchical file systems. Apple has complete control over app distribution and dominant market share.
For all these reasons, iOS seems like a horse that Apple will be betting more and more on as time goes by. Trying to make the Mac's OS too much like it would be like when Apple grafted the Mac user interface onto the Apple IIGS: novel, but ultimately a poor fit. The iPad already benefits from Siri and speech recognition, and its future lies more with these technologies than the keyboards of the past.