Russian Navy Nuclear-Powered combat AUVs?
How long it will take the West to develop such technology? Current Western submarine nuclear reactors were built for crewed submarines. That influenced their design in lots of ways, so a completely new reactor project would be needed. And new projects would have to overcome funding and human resourcing challenges. Not to mention a likely environmental backlash of putting unattended nuclear reactors into the world's oceans. Russia doesn't seem to care about that. http://www.hisutton.com/Russian-Navy-Nuclear-Drone-Submarine.html
So whether completely unattended nuclear reactors on autonomous submarines is a good idea or not, it’s something you are likely to see in the Russian Navy long before any western power.