It will never settle down over the short and medium term.
Leftists were calm only because they believed that society was heading more and more in their direction, with a lower and lower share of white people, fewer christians and more muslims. As long as they saw this development take place, they were happy.
Imagine the reasons a fairly rational person can have to become a terrorist or extremist. Let's say the person has some political goals and views.
As long as society clearly moves GRADUALLY CLOSER to that, they are far more likely to remain calm than to do, even if the SPEED might not be exactly as fast or slow as they want.
For example, let's say someone is rabid anti-tax. As long as the tax rate gets cut by 1% every few years, slower than they would like, they will probably stay calm, and just argue loudly that it should happen quicker.
But if the tax rate starts going UP, they are much more likely to start screaming or blowing up bombs.
A few decades ago, leftists wanted to commit global genocide, killing capitalist, civilian men, women and children in all nations in the world. They did not recognize the concept of civilians, they just wanted to kill everyone. That's not really/only an IDEOLOGICAL thing, it's very much a PSYCHOLOGICAL thing, the absence of sanity, reason, empathy and humanity.
A few decades later, why should the missing sanity, reason, empathy and humanity have suddenly appeared? It hasn't. They didn't have it then, they don't have it now.
So now you have a bunch of leftists feeling that a) the world is heading the opposite of what they want, b) they are utter and complete psychopaths.
Result: It will get worse.