Here's my prediction. It's going to go the way Cable TV has gone. In the next 5 years we'll see this sale strategy make it's way around the various tablet and PC companies (except for Apple).
Then it will be just generally accepted that Ads will be part of the user experience...just like cable. In the early days of cable we paid money to watch commercial-free broadcasting. That's why we paid for it. Now you pay money for what? just expanded programming, and you pay a LOT for it. That's why pirating is such a huge thing. It's easy and it's free.
Apple got it right with the iTunes store. Offer a price-point that people would be stupid not to pay, and a service that's easy as pie, and they'll go for it.
The rest of the world's strategy: we'll give you what you want, but it's going to hurt a little, and you still have to pay for it.
Another great example of the future of mobile computing (tablet or otherwise). Look at Dwell Magazine.
The first 4 years it came out, it was a 100+ page leaflet with brilliant articles and excellent photography.
Wins April 2005 National Magazine Award for General Excellence in the 100,000-to-250,000 circulation category.
Oct/Nov. 2005 issue...turned a new leaf towards ads and creates the same magazine, but with double the ads (in total a 250+ page tome) with the same amount of content as before.
Wins March 2006 Adweek 2006 Creative Team of the Year award.
Today, they reduced the issues back to the 100+ mark, but now have a better balance of ads and content. However, the content is no better than any other design magazines found in the check-out line.