DL and KL are also extremely closely tied up (DL phone agents can make changes to KL tickets, which I don't think is necessarily the case for all partners, and I believe if you call KL in the US you are connected to DL agents anyway) so I think even in more marginal cases, like if there's a weather waiver a few days in advance and you want to make changes, I believe DL could still handle it. Whereas for some other less-closely-integrated partners it might be a little bit more of a challenge.
If there is a change due to IRROPS, it's possible you could get moved to flight(s) with DL flight numbers, which would lose you the MQD and possibly RDM advantages you have on a KL flight number, but you should be able to fix that by claiming original routing credit after the fact.