In military terms, it's hard to say. America gets it in the neck, but western militaries are the most interested in keeping humans 'in the loop' because they define their professional identities by adherence to international humanitarian law. Self drive vehicles would make complex suicide attacks by irregular forces a lot easier, and suicide free. On the other hand, increased automation would allow high tech, low manpower forces (like the UK) to continue to throw their weight around, and the lack of casualties would bypass (to a greater degree) the traditional check on warfare which is coffins being flown home for a cause citizens don't understand.
The greatest effect is likely to be logistics. Consider the 'tooth to tail' ratio in contemporary militaries is usually something like 1 person fighting for 9 people supporting them. The UK found ways to increase its number of fighting troops in Afghanistan by outsourcing logistics to contractors (so 6000 people in country could all be fighting or close logistics support, rather than half of them driving trucks up from Pakistan). If that gets automated, then western militaries will be able to deploy more front line troops, weighted against support troops.
]]>