"Even if the alt-right becomes more popular, it will always have militant opposition willing to fight it at any cost"

According to Reuters at the very least 70 million Americans already agree with our goals. Assuming those are almost exclusively whites that's nearly half of American whites already providing us with implicit support, alt-right or no alt-right. Without a change, and all studies on diversity showing how cancerous it is a civil war is likely regardless of whether or not the alt-right exists.

"and of course a lot of minority people are unlikely to want to "peacefully" get deported."

This is just leftist wishful thinking to act like they have some spooky armed underclass ready to fight. Hispanics are by and large here for money, and money only. Make it less economically viable to be here, and they'll leave. But if forced deportations happen there's no reason to believe it won't just be like Operation Wetback when Hispanic citizens were forcibly deported. You'd be surprised how compliant people are when told what to do by an authority figure. Or did the Germans forced out of Bohemia after WW2 also start a civil war?