Blackberry will be lucky to get 5-10% of that. Most are non MDM managed activesync - then Mobile Iron has dug in a spot, and Airwatch is also in the mix.
The US is too anti blackberry it will take them a long time to come around. The IT leaderhip who made the decision to drop BES will not want to go back as it would be admitting they made a mistake - that doesn't happen. Those leaders will need to be replaced first.