There's a suggestion that blocking the US aid convoy from Columbia might lead to the first real clashes.
Desperate Venezuelans beg Maduro to accept aid coming across the border
If the protestors are willing to fight with the security forces, it will push those security forces to choose a side pretty quickly. Whatever their personal views, I wonder how many would stand by if their mates and colleagues were being beaten up.
Should any such violence break out, of course, it could be the trigger for wider civil conflict within the country, giving Maduro the opportunity to crack down even harder but at the risk of creating the civil war he 'could not rule out' a day or so ago. I don't see such a civil war or widespread violent protests helping his cause at all.