No doubt t if did go ahead things would change over time
however, BA would be getting a maintenance facility for the E jets and the ability to bring that work in house rather than outsource it which would save a small fortune.
Over time iv no doubt that the core BE flying would be kept and the addition of a
BA flight number might even increase numbers flying into MAN/DUB as it would allow easier through selling onto EI and other OW airlines.
Some routes would no doubt vanish. However I think that’s inevitable really as that’s probably the reason BE are as they are
cs