Reviews for Blackberry 6.0 have been mixed and it is doubtful that it will do much to stem the decline RIM faces in the consumer space. In the enterprise though, RIM doesn't face much of a challenge from the iPhone and Android devices. Just having Exchange Activesync built in does not an enterprise device make.
Enter Windows Phone 7. This Business Insider article believes that WP7 will pose a formidable threat to RIM in the corporate world. WP7 has Exchange Activesync built in, so that puts it on par with everyone else. Add to that it will support a number of policies only a domain administrator could love, tight integration with SharePoint and a user interface that is getting good reviews and you have a device that has no single competitor that can stand against it on all fronts.
Microsoft made significant inroads with Windows Mobile with enterprise accounts in the early part of the last decade. Think history will repeat itself, this time to the detriment of RIM? The chances are too high to dismiss out of hand.