Be careful what you wish for. I seem to recall that changes to the Access Network Frequency Plan mean that 35b cannot be rolled out in the UK now, even if someone wanted too. Plus having invested so much in g.fast, Openreach are not going to change, even if G.Fast flopped. As it is, we wouldn't have all these pods appearing if OR was not satisfied with results re: speed/reach.
Also, I don't think your statement that most network operators are going down the 35b route is necessarily correct. 35b has its own problems/limitations and is years overdue - just look at Germany were it now looks like its going to be 2019 before they can even start to deploy the service.
I think all Vodafone have really said is that we are going to launch a g.fast service, they just haven't publicly announced a date.. but then again, neither have Openreach said when G.Fast is going 'live' (rather than technically being a limited deployment).