BlackBerry has confirmed that their BlackBerry Link software for BlackBerry 10 does support Apple OSX 10.9 Mavericks. That is because it does not use Apple’s SyncServices to synchronize Contacts and Calendars. The sad part is that BlackBerry Desktop Manager for legacy BlackBerry devices with OS 7.1 and older is not able to sync calendars and contacts on OSX 10.9 due to it using Apple’s SyncServices. Everything else should work like backups and updates but not calendar/contact sync.
The other thing to note is that with OSX 10.9 it is only possible to sync with Apple’s Address Book/Contacts and iCal/Calendar apps. Synchronizing with Outlook and Microsoft Entourage requires Apple SyncServices so it will not work on OS 10.9 and later.
I wonder if it is possible for BlackBerry to get around Apple’s removal of SyncServices in future builds.