Six million U.S. broadband households are changing their 2011 consumer electronic purchase plans to get a tablet such as an iPad, which is cannibalizing sales in other device categories and inspiring an additional four million households who had no previous intentions to purchase a computing device this year.

That’s according to data from the Parks Associates’ research group (http://www.parksassociates.com). The group says the products at greatest risk of losing sales are other mobile Internet devices, including netbooks, notebooks, and e-readers. Tablets will also have significant impact on content publishing, including newspapers.

“One year after the launch of the Apple iPad, tablet adoption reached 13% of U.S. broadband households (approximately 10.5 million), slightly below current netbook and e-reader adoption rates,” says Jennifer Kent, a Parks Associates’ mobile research analyst. “Mass adoption of tablets depends on consumers’ ability to differentiate them from similar CE, and devices that overlap with the tablet will struggle to remain relevant.”

Of course, this is mainly bad news for other tablet makers besides Apple — and for PC makers. The Mac, so far, has remained immune to any dings from iPad sales. In fact, Apple computer sales are growing much faster than the industry average.

— Dennis Sellers