Haven't heard that they'll outlast the A380 but have heard they may be hanging around until 2023 or thereabouts to be replaced by the 777X. Perhaps retirement of both 744 and A380 at same time by 777X? Maybe I will get back to the 744!
(tell him he's dreaming).
Business plans are being put together re OJM/ OEB to keep them longer. Whether the plan is approved is another matter but someone is crunching the numbers.