I have also thought about the connection between low EROI and capitol costs. The simple example I use is that if energy is expensive you actually spend more on capitol investment to lower long term energy costs.

The example is buildings from the middle ages and earlier still standing in Europe. It worth it to build really well once. So to me the connection is that you quickly move towards a society of thrift or more correctly well spent money.

A throw away society like ours would burn itself up quickly in a low EROI environment. In a sense its a bit strange that you have to start looking back 500 years and earlier into history to try and understand how our ancestors lived and often thrived at the energy levels that existed at the time.

So I think you can see capitol cost rising quite a bit from todays levels since your building to last.