I was just thinking about this, I wonder if Nokia will be making a Lumia tab. It seems that cellular / LTE support seems to add cost to the end device. Cost would be critical. $299 is probably too high, and anything less means that MS would really have to subsidize it. I would pay $299, but don't see many others doing so. Even at $199 I think it'd be a tough sell against the Nexus 7. This is really the issue that even Android faced on tablets, you have to beat on price to get any kind of forgiveness for the weaker ecosystem. Long term I think that Android tablets will be more expensive, maybe not, I heard that there are revenue sharing deals that Google offers to OEM's from ads and the play store.
Either way, the MS model is more like Apple. I just don't think a Windows tablet can compete right now at $299.