There was never any advanced plan for G-BOAB to go inside T5, a few ideas were mooted but thats about it.
The plan all along was for it, under BAA guardianship, to be a gate guardian, but surprise surprise BAA have gone all commercial and think BA should pay for it to be a gate guardian, even though BAA are the guardians of the aircraft.
If I was a betting man; G-BOAB will eventually end up on the flight line at Duxford, more of a chance of survival there than rotting away at LHR.