There has been a surplus of B744s recently - given the state of the industry it's hardly surprising that the biggest beasts are hit the hardest and, of course, the same market conditions mean its difficult to move them on the used market. But the B744 has pretty much the lowest smc in the business and if you can fill 'em you'll make good money. The talk about possible used buys by CX, TG, VS and others are straws in the wind showing that some carriers are waking up to the fact that this lift is presently available at knock-down prices. BA have been looking to shed some 744s for years in view of the fewer but higher yield policy.
Aviation Partners Boeing are presently evaluating two possible blended winglet configs for the B744 (they've already flight tested winglets on the 74 Classic but that dog has truly had its day). Both configurations reduce drag resulting in a reduction in cruise sfc of 5% leading to increased still-air range of some 250nm and a reduction in required thrust resulting in reduced engine-costs. High altitude field performance is also improved. Blended winglets allied to low second hand values could give the 744 a significant increase in operational longevity (and no, I don't work for APB!)
There is no APB programme for the 777 and when TG asked Boeing if they could have a -200ER variant with a MTOW of 699,000lb so they could have Trents (the GE exclusivity starts at 700,000lb) Boeing said no and now TG have ordered 340-500s/600s instead. It could be that BA carry more weight but Boeing seem to be more keen to avoid offending GE than getting additional 777 sales!