I think the general argument is that infrastructure should be nationalised or communalised. There are examples of how this can work in Scandinavia.
This would decouple something like Openreach from being required to invest a lot of money now and having to earn a large profit every quarter. This can indeed work: pension funds might even be happy to finance it but at the same time you have to accept inevitable degree of political control it entails. You also need to balance social and political aims with (broadband to everyone, including those in the countryside) with the role of competition in spurring innovation: how do you get cost-effective solutions when FTTH either isn't technically possible or hideously expensive.
The UK's problem seems to me is that it has kept the monopoly going too long. Unbundling seems to have been both more effective in other countries in reducing prices and in encouraging investment in infrastructure.