The only aspect I can contribute to the BA debate is to ask a question.
Under the BA/AA arrangement/joint venture or whatever the correct term is, if (and it's a big "if") BA were to operate MAN-ORD or MAN-JFK instead of AA, would they have full connectivity from the AA hubs? In other words, would it be point to hub rather than point to point as it was for BA in earlier years to the US from MAN?
And how would BA's ability to attract premium traffic from MAN compare with AA? Whether it would be more or less attractive for pax is a different matter.
However, given the fact that it would require separately configured a/c, I don't suppose it's remotely a starter, or would a B787 be a consideration?
On a different topic, with probably more mileage in it, I see from a recent posting that the Norwegian rumour has raised its head again. But if a small base at MAN were to open, what routes would they operate? Could they find a niche, or would it be simply to compete with all the other airlines to the Iberian sunspots?