A quick google search came up with this from Ford's SYNC website:
Note: Apple CarPlay is available on 2017 model year Ford vehicles with compatible SYNC 3. Owners of 2016 model year Ford vehicles with SYNC 3 are required to perform a software upgrade and purchase a hardware upgrade to use Apple CarPlay. Please check back on the Ford Owner site this summer for more information about these upgrades.
I just went to my dealership and spoke to my salesman about this. While he doesn't claim to know the fine details, he estimates that the entire infotainment system may need to be swapped for that "hardware upgrade" and if that is the case, it'll be a very expensive thing just for CarPlay. But I'll remain patient for more information directly from Ford on this, as I really want to use CarPlay!