There's a post on the SE23 forum about this - apparently the latest commitment was to add trains to the existing overground routes, but no further discussion re: Bakerloo extension. Dear Boris mentioned it back end of last year. Here endeth my incredibly un-illuminating post. Apologies. Perhaps I should have gone back and cross referenced the aforementioned post.... it's just that my fingers are cramped from being crossed for so long in the hope that this might materialise.