Rockstar are adding a free new heist to GTA Online later this month, the first (I believe) since the original set. It’s called the Doomsday Heist, and puts you in an “unlikely alliance” to prevent San Andreas being destroyed. Maybe. Unless all the parties involved are just paranoid.
It’ll be released on 12 December. Here’s the blurb, plus a trailer. Looks like this is going to add flying (and sub-aquatic) cars to GTA Online.