Did they say 2047 instead of 2050 in order to make it sound like less of a guess?
I'd guess we'll see this between 2018-2025. The necessary technology is mostly here, the main obstacles to implementation are ethical and political. I would prefer not to see autonomous weapon platforms at all, but suspect that the tactical advantage they confer will be too great to ignore, especially when set against the lives of service personnel (of the side with the technology ready to go).
It's plenty likely that by 2047 we'll not only have fully autonomous combat aircraft but we'll have automated aircraft fabricators and aircraft fabricator fabricators.
It's almost as valid to say that we'll be fighting sentient robots in hand-to-hand combat in a post-apocalyptic world in 2047.
Hey, perhaps those are the decision-making drones they were talking about!
That's BDUF at its worst. Better to look at the technology needs of today while planning for flexibility and be able to iterate rapidly if we see a need for change down the road. If the US had locked itself into some grand technology road map in 1909 it would have most assuredly lost WWII because it could not have anticipated the technological needs of that war.