Just a random idea. Not based on anything so don't get your hopes up or don't get disappointed. :p

This might be a very cool idea imo. It's the kind of acts Tomorrowland likes to promote. Since it's rather "unique" (as in: a new "formation" - not implying this has never been done before) the audience won't be able to complain because it's not their favorite act or not the kind of act they expected for the live stage. I liked the Symphony of Unity back in 2015, even though they focussed a bit too much on recent EDM-bangers. The BBC Ibiza Prom shows much more potential by adding lots of classic tracks.

Probably not going to happen though since this would get a separate announcement. Can't imagine they announce this together with the other live acts.