Or, they will do what enterprises across the world are doing - open up a secure way for Android (via Touchdown, but some devices do whole-device encryption to a standard that counts now) and iOS to collect mail / contacts / calendars through MDM profiles, and when everyone switches away from Blackberry, shut down their BES environment and count the savings.
We did that last year in this here Fortune-20 company. The users love it, because they get to use a device they actually like, which they get to go out and choose. The bean counters love it, because we're not paying out the ass for BES and corporate-owned Blackberries that get dropped / crushed / lost. Instead, it's an easy-to-budget stipend to approved users, and a one-time capital cost to stand up the MDM solution, with a small recurring "annual support agreement" expense.