Support for pc98 has been completely removed:
It's still listed at:
among others ...
Add ia64 to that.
Note that new platforms like aarch64 should probably be added, too.
One rather visible place old platforms are still mentioned is in https://www.freebsd.org/doc/handbook/bsdinstall-hardware.html .
It's only removed in head. pc98 is still present in stable/11 which is still a supported branch, so remove it from the website and docs is quite premature. ia64 was removed in 11 so is a bit older, but most of the existing references on the website document this clearly.
The bsdinstall-hardware page is definitely stale. ia64 probably can be removed from that, but also arm, and aarch64 need to be added, maybe powerpc64, etc.