The PowerCore platform uses Motorola 56K DSP-chips, the industry standard for audio signal processing. As with hardware effects processors & synths from over 50 manufacturers, 56K DSPs utilize a processing technique called 'fixed point processing'.
Native VST, MAS, DirectX, RTAS and Audio Units plug-ins run using 'floating point processing' on the host CPU such as an Intel Pentium, Core, Xeon or IBM / Freescale (Motorola) PowerPC.
In order to execute code on any type of processor, be it a DSP or a CPU, the code needs to be written to conform to the processor. This means a native plug-in or an application running on a CPU and a PowerCore plug-in running on a DSP chip use completely different types of numbers to perform their calculations (fixed point vs floating point).
This difference makes it impossible to run native plug-ins on the PowerCore. It also makes it impossible to create a "wrapper" or utility to transform native floating point plug-ins into TC PowerCore fixed point plug-ins (and although it does sound rather trivial for non-programmers, it absolutely isn't), as a native plug-in or an application would need to be rewritten from scratch by the its original developer.