I had exactly same issue, updated with warning that nvidia dependancy breaks, after reboot black screen.
Now Im doing timeshift restore from tty (glad it works), but it takes so much time to restore, frequently throwing rsync errors Input/output (probably the reason is my old hdd), but it has no progress bar and no sign of how much is already restored and how much still have to be done. I’ve been running timeshift for 20+ minutes now and have no idea how much more it will be restoring all the data.
But I believe the issue was completely same - nvidia drivers, since I have nvidia 960 which has two display ports. So black screen from stable version - is not something good 
Hope such things won’t be put in stable updates anymore.