Yes, I imagine that their thinking must have been along such lines - but, as I've said, I wouldn't have thought that equipment replacement cost would be particularly significant - although (energy) running costs obviously would.
Again, quite probably, particularly if the land was worth good money (and could get appropriate planning permission).
However, don't 'we' have a need to maintain an LF/VLF communications facility for global communication with submarines ( for which the running costs would presumably come at least partially out of the defence budget?).