I traded m Blackberry 7250 for a Motorola Q. The main reason is because we had Exchange 2003 and couldn't justify a Blackberry server for the experimental use we had in mind.
It was much easier justifying a new phone and spend some spare time getting ActiveSync up and running. Blackberry may need to give away the server component to compete with Microsoft. The only model that makes sense is to Open Source the server and allow a community (strongly influenced by Blackberry) to support the "free" market and sell professional services for the Enterprise. Too many people use Exchange to continue trying to sell a costly proprietary solution that isn'tthat different from ActiveSync.
Most likely an Open Source community would be able to keep up and possibly surpass Microsoft's offerings.