That's something that's been around since the 1950s. Since a sub can't be expected to meaningfully recover a drone it launches, there's no functional difference between a 'drone' and a 'cruise missile' in this scenario.
Do cruise missiles have the ability to loiter very long before target acquisition? In my limited observation that has been one of the game changers in the war in Ukraine.
To me it looks like we’re rapidly nearing the point where we can target off of a shared coordinate system instead of painting targets or seeking RF/heat at which point the loitering munitions become much more useful even with small warheads.
Little loitering munitions like Switchblade don't have the range to be usefully fired from a sub; which wants to be hiding in deep water. Bigger UCAVs like Shahed or Bayraktar are essentially small ground-attack planes and behave like one, so if you're launching them from a sub what you're really making is a submarine aircraft carrier. All the evidence suggests that nobody wants a submarine aircraft carrier.
Take Bayraktar and try to fit it into a VLS cell so a sub can launch one: you first have to make the wings smaller because that wide lifting body won't fold up into the allowed diameter. But now that you've made the wings smaller, its optimal cruising speed is going to be higher, but you can't add a second engine or make the existing one bigger, so that means replacing the prop engine with a turbofan. And you've just designed Tomahawk.
