Less than two months ago, I had a MX IROPs affecting a TPAC itinerary. DL was willing to rebook me onto KE (booking it as a codeshare using DL flight numbers and Z class). However, the agent told me that they are no longer allowed to reroute through Europe to Asia, even in IROPs where it's DL's fault and the result is arrival one day later than necessary.

They also weren't willing to overbook the DL MSP-NRT nonstop in BE for me.