They can still make the EI flights to YYZ, SFO, and the later BOS, ORD and JFK services, as well as the second UA to EWR and the second DAL to JFK from DUB, probably a few others whose EOBT I can't remember.
Would Cityjet have a way of knowing what percentage of their pax would use these flights without interlining data? Same goes for the countless flights from AMS they could transfer to?
Many of us would crawl through fire to avoid LHR, with pre-clearance in DUB and AMS being such a pleasure to use in comparison, these flights MAY do better than we think......