I just read a headline that said Boeing had patented a drone that could fly and also turn into a submarine.  A drone is like a slow, controllable missile which carries even more missiles.  When a drone could also swim like a submarine, it can be even more lethal since it can go either way, air or water.  If a drone has stealth technology, can fly and swim, it becomes even more lethal than lethal.  Imagine what if a drone can fly just as fast as the fastest missile, with stealth, can fly and swim, how lethal such a drone would become?  I think in the future wars, technology that we are not hearing now will come out.  My puny imagination can already think up how crazy a future war may be if every single missile, rocket, and whatever is a drone.