Microsoft already tried Ultra Premium years ago and it failed. The Tablet PC didn't take off, and I don't think the Surface will either. I guarantee you that the Surface Pro will just be another machine that people leave behind at work, just like the DELL and Toshiba laptops I see my dad bring home all the time.
Difference is back then, the tablet PC was a laptop with a resistive touch screen. The OS used on Tablet PC's was basically XP with a tacked on touch UI, not an OS that was designed from the ground up with touch in mind. More importantly, there was no real tablet market back then. Totally different product and environment back then.
The real problem I see though is that Microsoft is trying to capture the younger crowd with the colorful keyboards and touchscreen. Obviously, the machine costs $500, and the keyboard $120. That is about the cost of a mid-range traditional laptop with a large hard drive and better specs. No parent is going to buy their kid that when there are much cheaper options like the iPad Mini/Kindle Fire HD 8.9" and a Bluetooth keyboard. They don't care about the apps, they just want something for their kid to be able to take notes, write papers on, and read their textbooks.
Without piggybacking off Windows 8 popularity or the Pro's success, the Surface RT will probably be another iPad competitor that fails to gain significant marketshare. And that has more to do with branding than price.
But the Pro version isn't geared toward kids, and isn't trying to compete directly with the iPad or any existing tablet. It's trying to create a new high end market, which I think there's a need for. I've left my iPad 1 in the trunk of my car for the past 2 months because the most I use it for is as an e-reader or browsing the web. Give me a slate form factor device I can use to create Office documents, edit CAD drawings, and program on and I'll buy it. There's nothing on the market that can do that to a capable degree right now.
The biggest criticism I have of Apple is as good as their OS and hardware is, they don't pay enough attention to software. They've made it so the app store is the only way you can install software on your mobile device. So you have a ton of apps for sale, but only one store, and the commoditization has driven down prices/profit and turned mobile software into a budget market. Because it's a budget market, no one's creating power apps. Because there are no power apps, people still need their laptops to do the more complicated stuff.
Ignoring upcoming hybrids like the Transformer Book, the Pro is the only tablet that will be able to do power apps, because it has the same tech as a midrange laptop (Core i5, 4g ram, HD Graphics 4000) and breaks the app store tradition by letting you install desktop software on it. I'm not guaranteeing MS will succeed but if you're someone who wants the tablet to be more than just a portable internet device, you'll probably be watching how the Pro does in 2013