I was searching through BB posts on google and found a post that suggested RIM sends out a message through bbm that states a little something about what to expect from bb10 and why people should stick with blackberry.. It could very well help save a few uninformed people from leaving.. And since they're having a few problems getting rid of their 9900's maybe send a few free devices to exhisting os5 users, or discount the price..
The problem I see is that most people would think such messages are the usual broadcast message spam, such as the "Jim Balsamic" spam message that was being circulated in various iterations.
the owner of a verizon store i used to go to said a while ago he wished he would have kept track of all the PIN's for BB's he sold so they can do blast BBM's to users about promotions, etc. free of charge. i think it's would be a great idea. just give people the chance to opt out if desired (but remind them it's 100% free).