AES-NI for x86 CPUs was going to be required for the next release of pfSense (2.5), but that requirement was dropped when the API that necessitated AES-NI was pushed back from the 2.5 release. AES-NI will probably still be a requirement at some point in the future.

AES-NI won't be a requirement for ARM CPUs - Netgate sells first-party ARM-based pfSense appliances that have non-AES-NI hardware crypto acceleration that they've confirmed wouldn't be affected by the AES-NI requirement. Not sure how that applies to third-party ARM systems.