I don't think we've fully solved the navigation problem, but I think we're close and it will certainly be solved before the power problem. A quick google got me this:
This work is amazing and I’m a big fan of Tedrake; however the gap between what you’re showing here and a drone a chases humans and slice their jugular might be bigger than you think. It’s very hard to extrapolate stuff like that.
https://www.youtube.com/watch?v=yOrtZ38olvc
and I suspect there are dozens of other similar projects out there.