I would expect that there will be a mandatory mental health revision out into this, as stated before and above. I would suspect ANY person who has had medication presented for any mental issue or has seeked psychological/psychiatrist assistance for any diagnosed personality disorder will be brought into question.
That is probably the only level of "no grandfathering" that may apply.
I agree in principle but we need to work on the wording or they will use it deny people who got help for stupid stuff like insomnia, or weight loss.
They already tried to use that as grounds to disarm veterans.
Anything that addressed mental health would need to go beyond simply denying gun rights to the dangerously unstable.
In both of the last 2 cases, Portland Or, and Conn. the shooter used stolen guns .
In China and Japan where guns are no available they use knives, hammers , cleavers, and poison gas.
The answer is not to try to keep these people away from potential weapons, that isn't possible.
We must find a way to keep them away from potential victims.