I'm really surprised it hasn't happened yet. Obviously I don't want it to happen either, due to A) killing people is bad generally speaking and B) the optics would be awful and the media would have carte blanche to crucify whoever did it and anyone even remotely/tangentially related.
For all of the leftist posturing that there are terrifying alt-right Brenton Tarrant clones around every corner waiting to yeet minorities and Democrats off of the mortal coil, I sure haven't seen that happening. Could it be that perhaps they're full of shit when they talk about how dangerous, deranged and violent the 'alt-right' is? Most of the guys that actually legitimately hate leftists are sitting around eating Doritos and watching them get their shit kicked in and bitching about society's current state in a Discord server.
All of the actual violence directed at Antifa/BLM was either violence that developed in their own ranks, accidental/negligent discharges, some Ethiopian guy that was driving too fast and that asshole that got popped a few times in NM for beating a man with a skateboard. The media easily could spin some of that shit, and doubtlessly they have tried, but when the video shows a person trying to disengage from the situation and they stop the pursuit with defensive violence, there isn't much meat left on the bones. They'll of course tell you that everything the police do is 'totally legit violence/war crimes' but, really, the cops have shown remarkable restraint. The cops could start beating them with feather pillows and these idiots would still scream "PO-LEESE BRUTALITY!" and rant about the Geneva Convention despite it not remotely applying to this scenario.
That whole 'vicious alt-right boogeyman' narrative is even less credible than it ever was. It's surprising though, you'd figure in the midst of all of this politically charged chaos, there'd be a sperg somewhere donning his black duster and trying to do his best Dylan Klebold impression.