Did BA have to give any undertakings to FlyBE when they sold BA Connect which may prevent BACF doing this?
Certainly ba.com lists flights from BHX which are operated by FlyBE as a BA codeshare - can't see FlyBE would be happy about BA poaching back in on those assuming there was such a market.
(I for one would rather fly on an E jet than a Q400 - both good aircraft, just my preference!).