Folding drones are still a relatively new introduction to the drone market, certainly for the larger models. Folding drones are a very exciting prospect though, because they offer the huge benefit and easy portability. Previously where you would need a cumbersome dedicated backpack for your drone and controller you can now just put folding drones in to a normal bag or just clip them on to a belt. You do need to always be aware of the controller size though as this will also have to travel with you, flight times are also a consideration because you may need to throw in an extra battery.
Folding drones have a bright future in mainstream consumer drones and will continue in success as prices come down. They do come in many sizes from toys to semi-professional drones, although currently much larger professional drones remain fixed. The two big folding drones to take the market by storm have been the GoPro Karma and the DJI Mavic. Many smaller toy / selfie folding drones have also since flooded the market, some of them small enough to fit in a back pocket.