I agree it won't be for a while yet. It got very close a year or two ago but MAN picked up pace when STN's initial MAG take-over FR growth started to level off. STN will pick up pace again though with LS and further increases from other carriers... I've no doubt it will inevitably happen at some point but certainly not imminently.
The one to watch in terms of rankings at the moment seems to be BHX threatening EDI's sixth place... some absolutely phenomenal growth there!