Very unlikely. With 3 (soon, sadly, to become only 2) A4s still being overhauled and operated on the main line, what would there be to gain? Bear in mind the point that you would have to replace a lot of metal to restore 4468 to working order again; indeed her running in the 80s was very tightly controlled and very much "Do just enough to make her safe, but no more". In addition, the modifications to take modern equipment like TPWS would be required. I just cannot see Mallard steaming ever again, tbh - not even for 2038. Scotsman was actually operational (just...) when she was purchased by the NRM. Different scenario altogether.