"Shot heard around the world"
What if Q is being literal here. What would stop everyone in the world to look and watch?
When JFK was killed EVERYONE stopped. That too was a shot heard around the world.
If they get desperate enough and figure they have no more options, they're going to go for it and shoot potus. That's really their only and final blow. It has worked for the cabal before, in stopping things that would've destroyed them (or delayed their plans significantly), so it would only make sense to me that this was 'in the cards'. Their final move.