Stelios himself was quoted at an event in Brum as saying "make us an offer we can't refuse" (to BHX or CVT). I remember being suprised at the baby rumours, and then they set up a base there.
Considering ongoing rumours about both of the above running down at EMA, I think that Easyjet would certainly mix things up a bit, but if they are just going to offer a few routes in from other bases, should they be discounted from CVT too? Again, the picture has changed here quite a bit since the airport was sold.
For BHX to continue without links to two prominent European capitals would not be good. BE have obviously looked at both, their a/c size would seem to satisfy demand, but they must have been scared off by competition at MAD, and possibly slot issues at TXL? Baby also appeared briefly on the SXF website about 2 years ago iirc, so again, they must have looked at this - and MAD too.
FR already operate SXF & MAD to EMA, so Easy would certainy make sense.