For the most part, no, it won't.
I personally feel that one instance of prevention for something like this justifies trying. Of course if you're sure that's a complete impossibility, I'd have to ask how you know such a thing...
Because the law cannot protect you from the actions of criminals....It's axiomatic.
So... in your (small) mind, what does the law do?
If metal health databases here crossed checked with national gun ownership database .... and if today's shooter had ever been prescribed medication for depression or manic depression, or been arrested, or been discharged from the military.... Then a red flag would have gone up and sheriff deputies could have paid a visit to his home, ask him to surrender all weapons in the home.
It's so ******* simple. We have the technology, we have the people smart enough to write thinking programs that talk to each other, exchange information and create a list of names of people who should not have handguns.
If you see a counselor and say something that indicated your dangerous (like the Colorado shooter) RED FLAG!!
Preventative.
We do it with sex criminals. Why not other dangerous people.
If you buy guns at a gun show, transport them across state lines for private sale, then you go to federal prison for 10 years. ENFORCE THE LAWS ON THE BOOKS!!