This article is great, really explains the challenges ahead for MS in the tablet market.
First, the survey you mentioned where people view their laptop and tablet as separate things, this implies that they WANT to keep them as separate things.
The fact is, the iPad is a terrible productivity device; next time you go to an airport, check out the people trying to use the iPad with a keyboard to do actual work, it will make your eyes water at how bad this experience is. For these folks, it would be interesting to introduce them to a Surface 2 with a type cover, miles ahead of anything available on the iPad.
Second, you are taking BYOD as a done deal in the enterprise. I have talked to several CTOs of large organizations, and they, to the person, _hate_ BYOD as a device strategy. The problem is, up to now they simply did not have much to offer as alternative. When your CEO comes to you with an iPad and says "get this on the network", this is a hard request to refuse if you don't present any workable alternative. This is just beginning to change with some of the newer Windows tablets, too early to tell if a real shift will take place or not.
I do, however, agree that this productivity tablets will probably ultimately only appeal to a limited set of users, but I do think in the long run, this could be a perfectly decent market for MS and its partners. Maybe ultimately 10% of the tablet market? That would be just fine for MS, selling, as you say in the article, millions of units.
I also agree MS is misguided in trying to compete directly against the iPad and low-cost Android devices. It is hard to imagine someone going into Best Buy, looking over an iPad, Android tablet, and Windows tablet, and ultimately choosing the Windows tablet for a consumption device.
Microsoft will lose if they continue to attack the "front gates" of the iPad and Android markets by trying to convince consumers to buy a Windows tablet for its entertainment/ media consumption chops. This is a losing game.
MS needs to offer an alternative vision of what these portable device can be, and the only game left in town is to push a vision of a real productivity device you can hold in your hand, connect to keyboard, and also dock with your 24" monitor at your desk. The good news is that the iPad and Android simply cannot do this, they cannot compete here; MS and its partners have this, admittedly niche, market to themselves