Forgive my ignorance, I know basically nothing but it seems like they are going out, what about going up? I did a very short search and found an entry on 3D IC

Forgive my ignorance, I know basically nothing but it seems like they are going out, what about going up? I did a very short search and found an entry on 3D ICs, one of the challenges was heat and I would assume latency but other than those (sizable seemingly) hurdles would 3D IC be a competitor to whole wafers?