The official minimum specs state that a GTX 460 is the minimum requirement.
The 650M has more pipelines/cores than the 460, so i think you should be able to run it. But I wouldn't try to go past low/med specs.
People with very powerful rigs are getting done over by the poor optimisation in the game...
Nvidia changed architecture quite a bit, so comparing pipelines and cores that way doesn't work.
Still not a good measure, but bandwidth and texture filtrate gives a better figure, and a GTX460 beats the 650M in both.
According to toms hardware GPU hierarchy the GTX460 is on par with 670M:
http://www.tomshardware.com/reviews/gaming-graphics-card-review,3107-7.html
Anyways, system reqs are always estimates and the game might still run at PS4/XBone settings on minimum few rigs (PS4 900p 30FPS).
It seems scaling is done well according to MICHAELSD, funny how a PC at minimum reqs can do 1080p where as the new console gen cannot