Complex sentence: The CRJ-700 has once again become the largest airliner type to serve Lafayette, until Delta begins 110-seat B717 service to Atlanta on July 7th, 2014.
Split into simpler sentences: The CRJ-700 has once again become the largest airliner type to serve Lafayette. However, that will change Delta when begins 110-seat Boeing 717 service nonstop to Atlanta on July 7th, 2014.