Container escape vulnerabilities are always a concern. A nonzero amount of those have occurred. In this area, spectre and meltdown have caused huge shockwaves

Container escape vulnerabilities are always a concern. A nonzero amount of those have occurred. In this area, spectre and meltdown have caused huge shockwaves (no pun intended) in terms of things commonly assumed to be safe turning out not to be. That's not to say it's not a good approach, just that it doesn't bring security concerns to zero.