Well the original Mac Book Air went off like a rocket but even at almost half the original price I don't think they are selling near as well as when they first came out. That said back in 2011 it seemed to be eating much of Apple's own lunch. If you believe the article they estimate sales of the MBA at 300,000/mo.
One other factor; PC sales we down last quarter. I'd hope that at least some of that was people holding out for the Surface Pro.
Of course like everything said here all of this is purely speculation... I think the proof in the pudding will be to see Surface tablets showing up in the next 6 months/year at Starbucks, business meetings, and sporting events where people think it's cool to use tablets as big cameras. The Zune never reached that type of recognition and I'd have to throw WP7 & 8 under that bus too though I keep looking for the latter and hope to see it prevalent soon.
Sent from my lonely Windows 8 Build 2011 tablet at Starbucks...