Both.  They could've done it in the past and they could do it in the future.  Trust me.  If they only play new stuff then they'll play to a dead crowd.  When I saw them in 06 the new songs were received by total silence.  I ain't saying the new songs suck, but they were not well received at the show I was at.  But Playing 5 or 6 new songs is ok and expected.  Anyone that expects more than that are gonna end up being disappointed.  You have to be realistic here.  So when I saw them they played 5 new songs which is fine.  From CD I expect them to play CD and Better.  Those 2 songs are a definite lock in my opinion.  But the rest they can alernate them.  That way during the tour they can play all the songs on different shows.  They need to surprise people.  I liked GNR's show in 06.  But had they played around with their setlist not only would I have liked the show but I would've been blown away and surprised.  Why can't they play If the world, Catcher, Twat, Prostitue (even if I hate that song), Locomotive, 14 years, Right next door to hell and the list goes on.  Surprise the fans and I can guarantee that people would be happy.  To me here are the songs that should be a lock and that the rest of the songs could be chosen randomly.

Welcome to the Jungle
Paradise City
Nightrain
Seet Child O' Mine
November Rain
You could be Mine
Don't cry
Chinese Democracy
Better
Patience

That gives them 8 to 10 songs that they can alternate every night.  Out of those 8 to 10 songs play 3 or 4 songs from CD and the rest from the back catalogue and you have a killer set  And I added Don't Cry even though they didn't play it in 06.  With that setlist and the rest of the songs where they would actually surprise the audience.  And if they would do that not only would I buy a ticket to at least 2 shows but I'd even enjoy Baz's set.