Acetic acid is made from methanol via the Monsanto or Cativa process. In turn, methanol is made via steam reformation from natural gas.

I'm not disagreeing with anything you said, but this economic advantage is underpinned by large quantities of clean, high EROEI feedstock.

This little discussion illustrates the problem with peak oil. Oil is really cheap in relation to non-oil feed stocks for almost any industrial process. When oil runs out, almost everything will be a lot more expensive. Some things will be more expensive than others and the overall differences will be small compared to what the price had been when oil was available. A big problem is to figure out now what will be cheapest then, in the future, using economic data from now, when the cost of everything is massively distorted by the availability of oil. We need to know what will be cheapest then because we will have very little time to do the development work when we start falling off the cliff.