I can see a future for microreactors powering container ships. Outside nuclear subs and aircraft carriers there are already nuclear powered icebreakers. https://en.wikipedia.org/wiki/Nuclear-powered_icebreaker
How much faster, is for somebody more knowledgeable than me to answer.
And now politics comes into play: these ships would have to not only have significant permanent armament, but given significant latitude to use lethal force.