Current (BBOS 5-7) can be connected to your company mailserver via BES for PIM synchronization. This is called "Enterprise Activated" and will provide secure communication between the device and the BES and LAN environment. Another advantage is low amounts of data beeing transmitted for PIM sync due to the efficient compression of BES 5.
As of PlayBook 2.0 and BB 10 ActiveSync will be the primary sync engine for Exchange and other ActiveSync compatible mail servers. Furthermore the device will support several other protocols (e.g. IMAP).
You have 2 choices to connect af BB10 device to your corporate mail server.:
1) Publish your Exchange (or other ActiveSync compatible server) to a public IP address and synchronize the BB 10 device as you would with any iOS, Android or WP8 device.
This will not require the monthly BES subscription ($20 in your case - we pay around $35!). You will of course need a generic data plan or WiFi.
2) Use BB10 with BDS (BlackBerry Device Server). This causes the *ActiveSync* traffic to be tunneled in the SRP protocol which runs through RIMs infrastructure exactly as the BES 5 traffic is. BDS does not sync anything, but terminates the tunnel and forwards the ActiveSync traffic to the Exchange server. This solution will (most probably - I am awaiting final confirmation) require a BES subscription and will be recommended for environments with a high level of security and management requirements.
Note: BDS along with UDS (Universal Device Service - MDM solution for iOS/Android) and BES 5 forms "BlackBerry Mobile Fusion". At BB10 launch this name will change to BlackBerry Enterprise Server 10 and a new version of this solution is released.
Hope this helps!