Hey guys,
I checked some dates on the BA site, and this is what I found: while the offer rules state that travel much be completed by Jan. 31, I found that if the outbound date is Jan. 31 or earlier but the return is after Jan. 31, flights still price at the $4999 fare.

I experimented with different return dates through Oct. 1, 2002-- about as far out as BA's res system goes now. All priced at $4999 plus tax = $5082 and change.

So you know, the official BA word is at http://www.britishairways.com/regional/usa/offers