My money is on JNB with 789 for a late 2019 start. Either EWR or IAD, maybe EWR marginally more likely. Both have 787 pilot domiciles, so ULH flying is possible.
In APAC, maybe BKK, but it’s hard for me to call that historic because UA was already in the market for a long time, and BKK-USA flights have been tried (and failed). I don’t think ORD-SYD; IAH already is a stretch for the 789. Not sure if ICN would qualify as “historic”, nor would any of the unserved markets in South America. EWR-CAI could on the table, but is that significant enough to warrant a press event with Oscar? I’m not sure. Certainly fits the bill as “historic” in one way.
I’ll also go out on a limb and wonder if this is the new longhaul LAX route we heard rumblings about earlier in the year? If that’s the case, then MAYBE LAX-BKK?
I’m sure someone will leak it soon...