I think the key word is "might". You would need to write a considerable amount of code to support EtherCAT in the lower layers of the Ethernet driver code.
You would be better off exploring hardware solutions with EtherCAT support "out of the box" so you can focus on developing your application instead of low-level protocol drivers.
Dynamic C 10.72 is closer to ANSI C90/C99 compliance than prior versions, but due to its quirks and inability to default all pointers to "far", it will still require considerable effort to port an EtherCAT driver to the platform.