I doubt this is what the author is alluding to, but a few years ago[^1] I read a proposal about CPU cooling using small-scale fluid tubes, much like a car engine is cooled. This would allow cores to be stacked vertically, much like HBM memory is stacked today. Perhaps this new development could allow better implementations?
[^1] https://arstechnica.com/science/2020/09/researchers-demonstr...