In my opinion no song needs to be dropped, that's not the point. Mark needs to develop an ever-changing setlist so that people go to different shows and have different experiences instead of seeing the same thing evening after evening, tour after tour, like they are stuck in a loop.
Years ago I used to agree with this, now I don't agree, but there is a reason.
I believe that is unfair that people going to different concerts in different places listen to different songs, everybody deserves to listen to the same songs. Many Spanish fans that couldn't travel didn't had the chance to listen "5.15.a.m" or "Back To Tupelo" during the Privateering tour. I was lucky because I travelled exactly to one of the very few concerts in which MK played them, but that was unfair to the rest of people that attented the rest of concerts.
I believe that a tour should have a setlist that gives equal chance to anybody anywhere to listen the same songs, but at the same time, I believe the setlist must change from one tour to the next in a big number of songs, leaving just the hits as the repeated songs.
The tracker tour and the privateering tour were so similar, despite the fact that 5 songs from Tracker were played, even the surprising add of "Your latest trick" or "On every street", the skeleton of the setlist was so similar that it was almost the same.
If you play 20 songs in a concert, for example, change 12 of that songs, and leave 8 hits between DS and MK solo career, change that from tour to tour, and that would be perfect.
But to play different songs from one show to the next, like Springsteen does.. It's not fair. Some years ago I went to see Springsteen to Madrid, and was a great show, but two days after, he played Bilbao and changed almost half of the songs, songs that I liked more than the ones I listened to in Madrid. Luck for Bilbao fans, bad luck for Madrid fans that wanted to listen some of the songs people from Bilbao heard, and maybe the other way around. That's not fair.