Some has asked about splitting BT and the like, but I did have some thoughts.
I do think that the technology has moved on and a heck of a lot of the lines in the country are capable of getting VDSL from the cabinet now. (Fibre To The Cabinet, Infinity, etc)
It seems odd that we even have a copper pair to the exchange - makes more sense to be the cabinet with an MSAN but sold by the likes of Openreach to any CP connection at the exchange with SIP for voice and ethernet port/VLAN for data. Why have a copper part to the exchange at all. Do an "outside the exchange" cab for direct exchange lines even.
In some ways new SOGEA will get close, but not offering the voice on the pair. And to some extent the idea of data only connectivity is sensible in the long term. However, there are silly people wanting old fashioned copper pairs to something I guess for a while.
I think the problem may have been regulatory - what you need there is OR to be operating this as a non-profit maybe. Though you have to work out where the capital investment comes in.
This seems more sensible than sub-loop unbundling to me. And could move on to FTTP or DP based DSL in the same way - hand over at the exchange as ethernet with SIP and all sorted.
Sorry if too technical - just a bit if techy rant this time.