It really depends on implementation - APEX itself is well optimized for CPU/consoles, but so far was used mostly for GPU accelerated eye candy (which one is meant to run perfectly on GPU only).
Point is, if devs will announce that ARMA 3 will use, for example, APEX Destruction module to add destructible buildings to the battlefield, there will be no reason to panic.
Also, do not worry about main physics layer - like character controller, vehicle physics, ragdolls - this types of calculations do not support GPU acceleration in PhysX SDK, so it will run on any CPU/system in any case