Microsoft company mobile director Andy Lees told AllThingsD in a recent discussion that once the timing is right, the company is planning to transition the Windows Phone lineup to more modern hardware features. Upgraded features will include dual core processors and LTE 4G technology.
Regarding advances toward 4G, Lees stated that Microsoft would have to make some design sacrifices in order to reach their 4G goals. Microsoft will likely wait for Snapdragon S4 chips (and related products in the lineup) which would already have LTE technology built in it. This would use less power, and would help Microsoft avoid things like extended battery packs.