> 1) ISPs agree not to compete; and --> probably not.
Except they currently do this, so... yes.
> 2) It is expensive for new entrants to build infrastructure. --> Yes, but if the ROI is sufficient, it can still get done.
> 3) Local / state government "franchise" agreements which grant incumbents monopoly (or near monopoly) status. --> the real killer. If the local government regulates you out of the market, it's game over.
It's not in the public's interest to allow a bunch of random companies to dig up our roadsides to lay a ton of fiber, over and over and over. So I don't see this changing.
2) It is expensive for new entrants to build infrastructure. --> Yes, but if the ROI is sufficient, it can still get done.
3) Local / state government "franchise" agreements which grant incumbents monopoly (or near monopoly) status. --> the real killer. If the local government regulates you out of the market, it's game over.