There are at least a couple of rotary wing UAVs like the K-Max and Fire Scout that are just retrofitted conventional airframes. So in a way it's almost like the technology skipped manned flight and was put directly into unmanned aircraft first. Perhaps we'll see some of it trickle back down as it becomes a more proven technology.

Personally I think the form that "jet packs" will eventually take is just an electric multicopter that you strap into somehow.