On the few times that I have had this happen where I had checked bags, the bags always made it their without issue, either on my rebooked flight, the next flight or sometimes a completely different routing.

One time I was on BOS-CLT-LAS, BOS-CLT was canceled and they rebooked me on the BOS-LAS nonstop some 6hrs later. I tried to recover my checked bag but the agent suggested I just leave it. if I tried to have it pulled there was more likely a chance that it would get screwed up somewhere in Boston. This was before they had baggage tracking online but I was surprised to see my bag waiting for me at the LAS luggage office it apparently had taken a route earlier in the day BOS-PHX-LAS.