Port the encryption and infrastructure, along with the marvelous keyboards they make to Android and I'm sure they'll survive. Or even grow.
I had a company-issued blackberry for about a decade. Each year or 18 months or so they would get refreshed, and I'd get the latest model. The early models were solid and great in almost every way, but each subsequent model was worse than the one it replaced. They haven't made a decent keyboard in at least 5 years. Their screens got more pixels and more colors each year, but the overall quality of the screens got slowly worse. My employer supports iOS now, and I'm happy to never have to touch a blackberry again.
I also did some app development for blackberry devices, and I can tell you without a doubt they have the worst platform, the worst tools, and it's obvious they never cared about making development workable. I only ever saw one third-party non-game app that was decent, and I estimate it took 15 people 6 months to build that. Compare this to some of the iOS and Android apps that a single person can put out with a couple weeks worth of effort.
Going with Android seems like it would be akin to starting over. I don't see what assets they have that HTC or Samsung don't have. They have their Enterprise Server thing, but I don't understand what advantage that has over Exchange + ActiveSync which every other platform seems to support. I would be happy to be enlightened about what advantages Rim might have left.