Is it possible a future firmware update will allow the X5 to capture 120fps like the Osmo's X3?

With the components in The X5, it should also be able to do 1080 60p HDV video: "The A9 also has built-in support for HDR video capture by combining two frames - thus 1080p120 becomes 1080p60 with HDR enabled"
http://www.anandtech.com/show/66 ... -gopro-hero-3-black

Yes, that A9 is in the X5.

gybo102 Posted at 2015-10-21 08:08
With the components in The X5, it should also be able to do 1080 60p HDV video: "The A9 also has bui ...

It's confirmed the A9 is in the X5 camera?

If so, X5 can never be firmware upgraded to function as a proper pro camera. Bummer.