I had this happen recently and was pleasantly surprised. I was bumped from NW HNL-SEA to HNL-PDX-SEA. The reroute had a 1-hr layover at PDX but I was able to get on an even earlier flight. Maybe it was the turboprop but I got this feeling that my bags were going to be on the original reroute. When I got to SEA I went to the NW luggage office and found my bags - locked up with other bags, behind the typical airport retractable banisters.

NW had printed out my reroute AND the earlier PDX connection as well ^ and attached it to the luggage ticket with my name and contact info. I was very impressed and delighted that they were taking so much care to prevent the loss of my bags.