There are some crash reports for FC4 on Windows 10. Most think that the drivers are at fault. (
Steam discussion)
One post in the discussion:
I've tried everything suggested here, even called Ubisoft-they said Far Cry 4 doesn't work with 10, Running NVidia v. 364.51 on a ASUS ROG laptop. All my other games work, I think it is Uplay? Thoughts?
Latest NVIDIA drivers have fixed the crash for some users, tho. Don't know about AMD, sorry.
There are many people running the game without any problems and then there are those that have run into some crashes. We cannot say for sure what'll happen to you.
If you do happen to upgrade, I suggest doing a clean install after that with fresh drivers. That should minimize any potential issues involving driver problems.