PM would make a really awesome, customer-friendly move if unused data purchased as part of a plan rolled over upon renewal. That's one idea.
Here's a second: A data plan with a one-year expiry such as the 365 day/20 Gb plan offered by Tbaytel for $125. If that carrier can negotiate a package like that with Rogers, then Telus should be able to offer the same here on PM.
Both of these ideas would still mean loads of data profit for Telus/PM, I suspect.