What Happens When Identity Range IsExceeded?
If you attempt to bulk insert more rows then available identity values between syncs you will get an error:


  The identity range managed by replication is full and must be updated
  by a replication agent.


The key here is to allocate range sizes large enough to accommodate for the amount of inserts that may occur between syncs.  You can specify the range sizes in article properties when adding articles to the publication.