Oh, in my view Guy is alluding to the actual ending tune, Piper To The End. Nevermind, it's great as well.
Maybe So Far From The Clyde will reappear in the 2020 World Tour! 
But I still do struggle with the fact that PTTE and SFFTC are quite sad songs, Going Home is a little bit more uplifting - especially prior the post-concert-blues.
Agree with you. Wild Theme is also possible. Not very 'uplifting', but also a perfect 'closer'. As I stated earlier, no MK/DS-concert is complete without one of the Local Hero-tunes as the closing tune.
In my opinion I'd rather see them playing some big hits as encores. Although we've heard them many times, BIA and SFA are perfect encores. Same for MFN or some other 'big' ones. A lot of diehards would prefer other songs, but a big part of the audience are 'tourists', and they expect big hits. It's better to play a (beautiful) song like Piper in the main set.
Regards,
Lars B.