If they were to open for a giant I would prefer it to be for a Led Zeppelin reunion (anything is possible now). I have seen The Stones about 6 times and to be honest the Bridges of Babylon tour back in the late 90's was the last time they were any good live... after that they were an embarrassing shell of themselves.
not gonna turn this into a Stones argument, but you are in the minority on that one. I've seen them and they are still great. their reviews are very positive overall.