Family plans worked well to create incentives for parents to outfit their children with mobile phones, by lowering the incremental cost of adding the next device. Family plans also discourage churn.
In the past, family plans have lowered barriers to use of voice and text messaging services, but mobile broadband has to be bought for every discrete device on the plan, with no advantage to the end user for volume purchases.
As users, especially the higher average revenue users, adopt and use multiple devices benefiting from mobile broadband access, the attractiveness of "family" data plans will grow. A big surge in tablet ownership in the December 2011 holiday and Christmas season illustrated what you might have expected, namely that wealthier households own and use more tablets and other gadgets.
According to the Pew Internet and American Life Project, adults over the age of 18 tend to own and use many mobile and portable devices. That is especially true for tablet users and e-reader users, who are more likely to own mobile phones, desktop PCs and e-reading devices, for example.