Right now, the "info:fedora/..." uri's are migrated into fedora 4. This isn't ideal. We'll want to map these to the new URIs for those items in fedora 4.
If Fedora 4 doesn't allow creation of links to resources that don't yet exist, we'll likely have to consider changes to the way migration-utils processes the repository.
One approach would be to create the target resource when it's first referenced and update the main processing to allow it to be updated when that resource is eventually processed. This would impose some limitations/complications on the id generation (ie, it would have to be pid-based).