Personnally I think it would be great to see the Shackleton back in the air.
A recent visit to Coventry, where the Shackleton sits just across from a Nimrod allows a very interesting compare and contrast of UK MPA technology. As I've also an occassional reason to wander through a P-8 it's even more staggering.
I think what got me most was how similar the Shack and Nimrod cockpits were....certainly compared to the P-8 glass screens