Yeah, that is more interesting. Was the arrival of the aircraft from previous flight also rescheduled? Was there an equipment change? Different tail number than usual? (Some of this you can only know after the flight.)

Since you say it's tomorrow, I was also about to ask if you'll be flying over the South China Sea but I see it's a trans-Atlantic flight now. Maybe you can try to ask the FAs once onboard?

The good news is, on a long-haul flight late departure doesn't necessarily mean late arrival: it might very land not much later than it was originally scheduled to.