Larger aircraft would only work on some of BMED's routes, if it were to get larger aircraft I imagine it would be to go elswhere as well.
I am sure BA does examine BMED type routes all the time but at the moment can't see where they will get the spare larger aircraft from as unlikely they would pull one of their routes to free up an aircraft for a BMED type route. Anyway, maybe I am wrong, will wait and see.
Still can't see where the news of an anouncement on Dec 18th has come from, companies don't set a specific date to announce plans about their future etc. What happens if the plans don't work out by that point?
Would look a bit silly if they said they would announce such and such on a date and then the plan didn't work out in time so there wasn't anything to announce!!!!