I've had this feeling for the past several months that Apple was converging on a hybrid device. A hybrid device would be a combination of an iPad and a laptop, sort of like a MacBook Air, but with a detachable screen, you'd think this would make sense, but after Tuesday's comment by Tim Cook regarding the tradeoffs and how that convergence may not be good to the user, I think we're all having second thoughts.
I initially thought that Apple was moving towards convergence when they started making the controls in OSX behave more like those on the iPad, even the scroll control matched the iPad (despite it being opposite of what it should be on screen). From what I understand about Mountain Lion, it even brings iOS and OSX closer together. You combine these changes with the very popular MacBook Air and you'd think that the leap from MacBook Air to iPad hybrid wouldn't be big one to take.
While most will admit that the iPad is a very useful device to have around, it's great for scanning emails, websites, apps, etc… It's not that great at taking notes and such, to really take notes well you need to have a keyboard (at least until we have neural transmitters implanted in our brains). Some people can take notes quickly using the iPad's built in keyboard, but most can't, as a touch typist I have a very difficult time typing on the iPad. Then once you add a keyboard you'll want to add a mouse (which the iPad doesn't support), if the iPad did nothing else for convergence other than add mouse support, this would solve many issues, I could use a BlueTooth Keyboard/Mouse and then use my iPad as a monitor. I recently had a friend ask me if he should get an iPad or Laptop for his daughter as she goes to college, I suggested a Laptop and went further to say that the iPad while great, would make a frustrating experience for writing papers and such, yeah there are tools like Pages for the iPad, but let's be honest, Pages isn't Microsoft Word, if you need to email a document to your teacher and you send a Pages file, you'll most likely get an F for the paper. For a laptop I suggested the MacBook Air, mainly because it's small, light and especially for a woman, it could fit very nicely into a larger purse.
There are several problems with convergence, until processors/drives get faster, smaller, cheaper, efficient etc… it's going to be difficult to build a device as compact as the iPad, even though the system could be docked with a keyboard, most of the power would still need to be in the tablet itself. The keyboard could offer more disk space, but in reality you'd want the tablet to be a self contained unit. Until you can make a device small and light enough and still powerful, making a tablet that is converged with a laptop is going to be tough. Note that I realize it can be done and has been done with Microsoft and Android devices, I haven't played with the Android device, but a Microsoft device I played with was thick and heavy when compared to the iPad, though it was very cool to play with a full copy of Windows on a tablet. So the unstated rules of the game are "It needs to be at most as big and heavy as the iPad 2/3". I think in the next 2-3 years this will be doable.
A smaller possible problem with convergence on Apple's part is that it would put the iPad in direct competition with Microsoft laptops. Currently Apple dominates the tablet space, but can they really compete with Windows? I don't think this is an issue about "Which OS is best", this is more of an issue over will users be willing to migrate to a new OS. I've been running on OSX about 98% of the time for the last 2-3 years, while OSX has it's plusses, it's really just another OS, I think what makes OSX so nice is that Apple combines it with first class hardware. Anyway for Apple to go head-to-head against Microsoft would be a huge gamble for them.
There's a bigger reason against convergence though, this is a business reason by Apple (though it will be spun as a user concern). When you use a laptop you get software on it by downloading it from the web or installing it from a physical device (CD-ROM usually). When you use an iPad you get software on it by downloading it from the AppStore (unless you jailbreak the device, but I'm considering that against the rules for now). So if Apple builds a hybrid device, they will either need to force the device to use the AppStore, which means that some of your favorite non-app tools would need to move to the AppStore (or not be available) or Apple will need to allow the user to "side load" programs to the device, which means that there's no longer a reason to have the AppStore.
This last point is where I think the issue really lies, convergence isn't a "user" issue for Apple, though it could be spun that ensuring all software that gets to the device has been approved by Apple, but instead it's a business issue for Apple. Apple doesn't think it could sell a hybrid device that will not allow you to install your favorite software on it, unless of course that software resides in the AppStore. I think when push comes to shove, Apple knows they'll make much more money from the AppStore than it will off of building a try hybrid device that requires them to gives up their control of the ecosystem and in the end it's the ecosystem that makes iOS so successful.