We have the technical means to produce brain emulations. It requires just very straightforward advances in imaging and larger supercomputers. There are various smaller-scale brain emulation projects that have already proved the concept. It's just that doing that at a larger scale and finer resolution requires a lot of person-years just to get it done.

EDIT: In Rumsfeld speak, whole-brain emulation is a series of known-knowns: lots of work that we know needs to be done, and someone just has to do it. Whereas AGI involves known-unknowns: we don't know precisely what has to be done, so we can't quantify exactly how long it will take. We could guess, but it remains possible that clever insight might find a better, faster, cheaper path.