Hie,
To answer your question, if you buy the IP core, it cannot be directly ported over to your ASIC design to implement MAC, PCS and PMA layers. Only the MAC and partial of the PCS are implemented in the core logic; which you can port over to ASIC. The PMA and part of the PCS is implemented using the transceivers of the FPGA which are hard circuit and not fully implemented using HDL.
Also, Seriallite III offered with the Intel FPGA was never designed with intend to be ported over to ASIC. Hence, the challenges and limitations are unknown.
Regards,
Nathan