An awful lot of this depends on Ofcom. They have tried to deliver low prices for consumers, regulating at the retail level, and delivery competition at the wholesale level regulating there. This works for delivering cheap, lousy LLU but ruins the return on investment for infrastructure builders and acts as a disincentive to them.
The question is a simple one: are Ofcom prepared to allow broadband bills in the UK to go up as usage and speeds go up? They don't even have to do anything to make it happen beyond allowing BT to withdraw copper and replace it with fibre.
The single greatest obstacle to Matt Hancock's vision is Ofcom. The two main infrastructure builders, Virgin Media and Openreach, would love to be both invest more and in turn charge more to recoup that investment. The big groups lobbying Ofcom the other way are TalkTalk, Sky and to a lesser extent now they've bit the bullet themselves Vodafone.