A week in, and it's tough to say if this particular incident will lead to positive change, but right now it seems like there's no way this genie is going back in the bottle. The snowball has started rolling, and there will continue to be copycat attacks (who knows if/how many will be successful, but I'm confident this will lead to more attempts). Maybe there truly is no number of elites in scummy business models who can be targeted to enact change and the USA will descend into something a lot messier, but there's no way to walk this back. The results may ultimately be a relatively positive, relatively peaceful, and relatively successful trustbusting progressive movement a la the Roosevelts (though... for the gals pulling 1789 analogies out of their hats, I'd recommend giving some thought to what the following 50 years of French history looked like before endorsing that particular path of social change), or it could lead to a complete crackdown and tyranny (of which there are countless examples). The elites have ghoulishly lost sight of noblesse oblige, and the people seem just about ready to remind them.
Even in the worst case outcome, the immediate net good in my eyes is that it provides disaffected young men wanting to go out in a blaze of glory a better target than a school classroom.