Originally Posted by Often1

Flights are very unlikely to be sold out and even less likely to be overbooked.

DL has most likely locked inventory so that it can consolidate underperforming flights, e.g., have availability meet demand. Once that occurs, the remaining inventory will go back on sale in whatever fare buckets the new RM/IM suggests.

With constantly changing schedules, I would not book a connection when there is a nonstop. What is now a 2-hour connection, could easily become 8-10 hours or an overnight.