Re: Oh well
No, you will not get a 50V pots line with fibre, instead at the premises you get an Optical Network Termination unit with a Battery Backup Unit which contains rechargeable cells. These will locally generate the 50V required to operate legacy POTS termination equipment. Openreach will roll this out to every line, completely removing all the copper network.
The exchange will only need a router with all optical interfaces.