Not really so much a DLC (well maybe it is) but I’d like to see some of the old FSX styled missions. Maybe even the exact same missions, although updated/remade/remastered or whatever.
As for the Blue Angels idea, flying in formation is next to impossible with the servers the way they are. The constant disappearing of other people makes this type of thing extremely frustrating. They need to look at sorting out their servers before attempting anything like this.