OK, I have my own opinion about that. I have never used a Blackberry but they were clearly brilliant at what they did. I have a Nokia E63 with a qwerty keyboard, which I switched back to recently after a few months of android. For texting and e-mail, it's absolutely outstanding. For web browsing, too, it is adequate. Steve Jobs with his reality distortion field convinced the world they don't need physical keypads. He was wrong and they are wrong. Samsung has already successfully brought back the stylus (the Galaxy Note lineup is an astonishing hit and now other manufacturers are following suit, including Microsoft), and I am hoping there are more and better phones in the future that have Blackberry-quality or Nokia-quality qwerty keypads.
Back to tablet-laptop hybrids -- it depends what you use the laptop for. What we already have on the market (Android tablets or iPads with 3rd-party keyboard-cases) is already very useful to many people. Here in India I see many field workers carrying around cheap ($150) 7" android tablets in cheap ($10) USB keyboard cases, as an alternative to laptops. Much lighter, the battery lasts all day, there's internet everywhere via 3G or GPRS, and what comparable product can you get for $160? It makes a huge amount of sense for these people, who only need e-mail and a web browser. If you could also have productivity software, it would make sense to many more people. With Windows RT, you can have office software that's, if not the same as the "full" (Windows 8) version, at least "good enough". So I do think it is going to be very attractive to many people. And with Android, you can do it under a linux chroot (I do) but the manufacturers are missing a serious trick by not pushing this hard enough or pre-configuring it to make it easy for users. Or maybe they think QuickOffice and such things are "good enough".