DL is making a definitive bet that long haul international travel will not recover to any degree of profitability for 3-5 years minimum.
This is also a bet by DL that TATL travel will come back faster than their current suite of long-haul routes to Asia and JNB.

They are probably right since we are going to see prolonged restrictions like mandatory 2 week quarantines for arrivals and wildly differing definitions of immunity for at least 2 years.
Countries who have a strategy of suppressing the virus at all costs will not co-mingle with countries that have a higher percent of exposed citizens (although likely immune) for a long time. The strategies of how to "handle" the virus are more aligned between the US and Europe compared to the US and Asia and even Australia thus far. And those routes that do continue will be served just fine with the A339 and A359.