Unsurprisingly our LHR-ORD flight was switched from a 380 to 789. I noted that the earlier daily flight on the 744 was cancelled on our departure day (19th).
Booked those tickets in January and now there is no real reason to go as two of the three events were postponed for a year and I really don't want to take the risk in the US right now, so will probably take the voucher and shift the flights to next year, same dates.