> With the line-sharing rules, it was no longer financially viable for the telecoms to invest in infrastructure for common carrier services that they could no longer sell at a premium.

I completely agree, it's no surprise that a business that naturally tends toward a natural monopoly has a hard time with long term investments if the investors are chomping at the bit for immediate ROI. Hence the need to treat infrastructure as a local utility, regulate it as one, and fund the infrastructure improvements with bonds.