That is, if they are going to either remain in existence or get transferred to another scheme. I have burnt all of my DC miles now, although if there will be a decent transfer, I will be cancelling my bookings.

I suggest you just fly OU to ZAG. It's not bad.
If you are desperate to fly with BA, then LGW-DBV and then connect from DBV on OU to ZAG.
I must warn you that if you decide to do that, you will need to book early, as LGW-DBV in the middle of summer gets horribly expensive. c. £750 return in ET was hardly unusual last summer.