I'm not sure a lot of people understand the modern tech world on this forum. A modern smartphone is basically a computer and you can do anything with it that you can do on a PC, except for a few specific things.
I've travelled all around Australia 16000 klms with my smartphone being my main computer. Using it as a navigator, finding camping grounds, places to eat, places of interest and booking camping grounds.
Every now and then I used it as a hotspot for my Netbook, but that was hardly ever, I found the phone to be main computing device.
I also use tablets, hate saying it, but iPads. The 10" iPads really are too big when you're travelling overseas, okay if you want to lug a backpack around all day, but you're better off with a phone or even better a 7 or 8 tablet. The iPad Mini is actually a tad large, and a better idea would be something like the Nexus 7.
I've seen plenty of people at Airports lugging a 17" laptop around, they're usually tethered to a pole sucking up airport power, it's the most ridiculous sight I've ever seen.
At the moment I think it's still better carrying two devices, but I can see people being satisfied with just a phone or a phablets.
The world is moving fast, every year I carry a new gadget overseas, usually lighter and faster each time. My wife is on my back again right at this moment wanting to go to Spain and Portugal. So I could be looking for a new gadget very shortly or buy one overseas.
I don't know what's going to come out on top, or whether it will be a variety of devices. I'd hope to see the Surface Pro for business people and then a variety of devices below that for more casual users. Also even a bigger Surface Pro for specific purposes.
There are some things the smartphone form factor is good for, and things the tablet PC/laptop PC form factor is good for. I don't prefer to do serious stuff on my Windows Phone because it's handy, if it's just filling in some numbers into an Excel sheet or a Word document, OK. But if it's like doing internet research, browsing, or hardcore tasks, a smartphone just does not cut it for me.
The reality is that the vast majority of people use Android/Apple tablets and the like because they are not interested in doing serious stuff, the devices are social tools. I went to a wedding recently and one guy there was using his iPad to video the wedding. I thought it kind of weird, but then I've seen videos taken with the iPad and they aren't too bad, if you're not into cinematography, and they are immediately viewable and can be easily sent to facebook or whatever.
I can absolutely assure you that most people would love to be able to do serious stuff, it's just that they can't. I might be wrong but I think over the next couple of years you'll see many, many people jumping onto Surface Pro and even Surface RT as well as gadgets made by the OEMs.
I doubt very much that people will suddenly start abandoning their Android/Apple devices for Windows tablets etc. They are so entrenched in these devices and the ecosystem, especially Apple, that there is no reason for them to change. Microsoft hasn't introduced anything compelling enough for any of these users to contemplate change, in fact, the marketing has probably convinced most that there is nothing to be gained with change.
I mean, look at the Microsoft fanboy on this forum, despite the religious fever with which he promotes Windows 8, he still keeps buying every new Apple and Android product. I argue about Microsoft's direction etc, but do not own one single Apple/Android device, everything is Microsoft. However, I can see what the general populace wants and is happy to own and Microsoft comes a distant third in their choice of product.