Besides the "Cine" mode, is there any way to control (slow down) the Yaw speed on the Mavic Mini?  It still seems too fast for me, even in Cine mode.  Is it possible this could be addressed in a future firmware upgrade?  Does anyone else have a problem with the Yaw speed being too fast, or is it just me?

Yes, is stated in page 33 of the manual.
Advanced settings within the Gimbal settings, you can change speed and smoothness.
Within the DJI FLY APP/ Control/ Gimbal settings / advanced.

Yaw speed in Cine mode seems really slow, why do you need it to be even slower? You don't have to push the stick all the way to the left/right

Hi. Thank you for posting your inquiry. For the the Cine mode the yaw speed is fixed and dependent on the physical input on the control sticks as Ice_2k said at post #3. If you want to have the yaw move slower you may want to use P mode manually then follow the recommendation of InspektorGadjet at post #2 for adjusting the gimbal on how slow you want the gimbal to respond on your input. Thank you.

You can try the rubber band trick buy hooking a rubber band to the yaw control stick and pull it to the left or right.

InspektorGadjet Posted at 2019-11-26 02:06
Yes, is stated in page 33 of the manual.
Advanced settings within the Gimbal settings, you can change speed and smoothness.
Within the DJI FLY APP/ Control/ Gimbal settings / advanced.

Gimbal has nothing to do with Yaw. I have the same problem as OP. I find Yaw speed even in cine mode too fast when I'm fully deflected. In P mode, it's just too fast for a smooth video. But I sometimes need to stay in P mode because in C mode the aircraft moves just too slow forward.

There is no option (similar to gimbal speed adjustment in settings) to slow down the yaw.

And yes I realise if I move the stick less it will move less, but that just doesn't give a smooth video when I have to yaw. For me for example, the perfect yaw speed would be to have the C mode yaw speed when I'm in S mode. P slower, C even slower.

DJI, any way to implement a yaw speed setting similar to the gimbal speed setting?

Just like the Mavic Air has: https://youtu.be/jB4LobFCL_8?t=29