But the iPad won't stay the same, either. The new A7 chip in iPhone 5S is, as was pointed out during the keynote, a "desktop class" processor. I think all the hardware is in place now for iPad to act as a convertible tablet / laptop. Apple just has to write the software for it. And if Apple lives up to its past standards, it will mostly just work from day one, not be a half-baked mess like Windows 8.
I do think convergent devices are the future, but Microsoft's mistake is pushing devices to market before the hardware technology is quite there. They spent a decade pushing tablet computers while they were still too heavy, too limited and too expensive, and was blindsided when Apple introduced the iPhone / iPad. They are doing the same with their push for Win8 hybrid devices. And personally, I think history is going to repeat itself, and Apple will be the first to make a hybrid device that just works, leaving Microsoft's attempts in the dust. But we'll see what happens!
I really don't know about that. The A7 chip indeed seems to be very fast, but I don't know if it is desktop-class. The great problem is the software, not the hardware. While iOS 7 was a major overhaul in terms of design, functionality was not very much improved. Multi-tasking is still not multi-tasking. There is no file system. No mouse support. And there are really no decent office apps for it. Even Apple's iWork, which is the best mobile office suite to date, is quite limited compared to Microsoft Office (and I'm skeptical about is evolution, since Apple hasn't upgraded the Mac version in four years).
Apple's approach has been to keep the devices separate. Apple will not make a toaster-refrigerator, as Tim Cook once mentioned. Every device has its purpose, its "soul". And this philosophy is not compatible with the release of a tablet-laptop, a convertible device.
And, if Apple manages to make the iPad a convertible device, what will happen to Macs? Apple will either converge iPads and Macs, or the Mac will disappear.