Realistically speaking:
One Tree Hill
Gone
Dirty Day
Those three I can see actually fitting into the setlists they play now. I know they played One Tree Hill at some point (probably in New Zealand), so that one isn't too far fetched to show up on a later tour. The other two definitely ought to though. You could have Gone early in the set, about the fourth or fifth song, since we know they like to come out with guns blazing (by which I mean up tempo tunes). Dirty Day would be a great choice for an early encore tune.
These aren't three songs that I'd want incorporated into a static setlist. If they have slots in the show where they could play something without having a precise and finely tuned light show, they could have 9 or 10 songs in their pocket to select two or three from each night. This way the sets can stay fresh.
I really hope the next tour isn't as much of a spectacle. Don't get me wrong, I've loved every stage from Zoo TV on (Elevation excluded), but it'd be great to just have the guys out their playing songs. This would encourage setlist variation and could well mean that we wouldn't ever see the same set twice in a tour. That would be the ideal situation for me.