Volunteers to tackle some of the following would be welcome:

Support the "traditional" BSD  -A flag (incremental loading).
(There is a -A flag in ld now, but it is used to specify the
architecture.  That should probably be changed.)

Shared library support is missing.

Support for dynamic loading (a la dld, but bfd-based) would be nice.

Avoid re-open (and re-seeking) output bfd and archives.