Assuming you meant the next Xbox; why do you think MS will price it below Sony? because the new Kinect aint going to be cheap, and if MS somehow do set base model price at $349 i can see a Strong possibility that Sony will match it.
Sorry, yes of course I mean their next-gen iterations.
I think the new Kinect will in fact be cheap. I am assuming it won't have a motor this time, and most, probably all of the processing will be done by the next Xbox. It leaves a number of components that may well be equal to those in PS Eye 2 (which has two cameras) and both of them are likely going to be so cheap to build that they'll hardly have a significant impact on the total price. If either of them costs more than $20 to make, that would surprise me, and therefore the difference has to be less than that. Assuming the last leaks are correct, I think Microsoft has done a lot to try and undercut the PS4, expecting to have to work at that much harder than last time.
That said, I definitely also expect Microsoft to try a subscription model - it just makes a lot of sense to do that combined with Live, given where they are coming from.