Well if one world do increase presence at MAN they will require feed and flybe is the airline of choice.
They already codeshare with BA (LGW), CX, EY, AY etc
If the AA/BA JV are going to look at increasing MAN i would expect to see either AA & BA codesharing on BE ex MAN or IAG trying to buy up BE. IAG do seem to be in the market to buy again currently.
cs