Apple's offerings next summer will include a Verizon-only iPhone compatible with the carrier's CDMA network technology. Dual-mode chips, announced this week by Qualcomm, might not be ready for prime time in 2010. Neither will LTE network technology, which is expected to enter widespread service in 2011.
This leaves Apple with only one option to expand to the largest US carrier after their exclusive contract with AT&T ends next year. Build a Verizon Wireless compatible iPhone.