I recently did a recce of a new (ish) road here which links to the Quebrada de Humahuaca to Calilegua Cloud Forest for the first time.
The road actually opened in October 2019 and links Santa Ana (roughly 120km from Humahuaca, way beyond the Serrania de Hornocal) with Valle Colorado in Calilegua.
There was only 15km missing, but there's a descent of roughly 1,400m, and as you'll see from my photo, the road is cut into along sheer cliff, so it was quite a project.
There is also an excellent, and easily accessible, section of the Inca trail along the way, and a spectacular change in scenery as you descend from the mountains into the Cloud Forest.
More info on my blog and webpage.